diff --git a/src/layer/concat.cpp b/src/layer/concat.cpp
index 11071bdee..fb3a040b3 100644
--- a/src/layer/concat.cpp
+++ b/src/layer/concat.cpp
@@ -23,6 +23,12 @@ Concat::Concat()
     one_blob_only = false;
     support_inplace = false;
     support_vulkan = true;
+
+#if NCNN_VULKAN
+    pipeline_concat = 0;
+    pipeline_concat_pack4 = 0;
+    pipeline_concat_pack4to1 = 0;
+#endif // NCNN_VULKAN
 }
 
 int Concat::load_param(const ParamDict& pd)
@@ -261,46 +267,126 @@ int Concat::forward(const std::vector<Mat>& bottom_blobs, std::vector<Mat>& top_
 }
 
 #if NCNN_VULKAN
+int Concat::create_pipeline()
+{
+    std::vector<vk_specialization_type> specializations(1);
+    specializations[0].i = axis;
+
+    // pack1
+    {
+        pipeline_concat = new Pipeline(vkdev);
+        pipeline_concat->set_optimal_local_size_xyz();
+        pipeline_concat->create("concat", specializations, 2, 11);
+    }
+
+    // pack4
+    {
+        pipeline_concat_pack4 = new Pipeline(vkdev);
+        pipeline_concat_pack4->set_optimal_local_size_xyz();
+        pipeline_concat_pack4->create("concat_pack4", specializations, 2, 11);
+    }
+
+    // pack4to1
+    {
+        pipeline_concat_pack4to1 = new Pipeline(vkdev);
+        pipeline_concat_pack4to1->set_optimal_local_size_xyz();
+        pipeline_concat_pack4to1->create("concat_pack4to1", specializations, 2, 11);
+    }
+
+    return 0;
+}
+
+int Concat::destroy_pipeline()
+{
+    delete pipeline_concat;
+    pipeline_concat = 0;
+
+    delete pipeline_concat_pack4;
+    pipeline_concat_pack4 = 0;
+
+    delete pipeline_concat_pack4to1;
+    pipeline_concat_pack4to1 = 0;
+
+    return 0;
+}
+
 int Concat::forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>& top_blobs, VkCompute& cmd, const Option& opt) const
 {
     int dims = bottom_blobs[0].dims;
-    size_t elemsize = bottom_blobs[0].elemsize;
-    int packing = bottom_blobs[0].packing;
 
     if (dims == 1) // axis == 0
     {
         // concat vector
         // total length
+        size_t elemsize = bottom_blobs[0].elemsize;
+        int packing = bottom_blobs[0].packing;
         int top_w = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
-            top_w += bottom_blob.w;
+            elemsize = std::min(elemsize, bottom_blob.elemsize);
+            packing = std::min(packing, bottom_blob.packing);
+            top_w += bottom_blob.w * bottom_blob.packing;
+        }
+
+        int out_packing = top_w % 4 == 0 ? 4 : 1;
+        size_t out_elemsize = elemsize / packing * out_packing;
+
+        // TODO pack1to4 and pack4to1to4 make sense ?
+        if (packing == 1)
+        {
+            out_packing = 1;
+            out_elemsize = elemsize / packing;
         }
 
         VkMat& top_blob = top_blobs[0];
-        top_blob.create(top_w, elemsize, packing, opt.blob_vkallocator, opt.staging_vkallocator);
+        top_blob.create(top_w / out_packing, out_elemsize, out_packing, opt.blob_vkallocator, opt.staging_vkallocator);
         if (top_blob.empty())
             return -100;
 
-        cmd.record_prepare_transfer_barrier(top_blob);
+        cmd.record_prepare_compute_barrier(top_blob);
 
-        int dstOffset = 0;
+        int woffset = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
 
-            int size = bottom_blob.w * bottom_blob.elemsize;
-
-            VkBufferCopy region;
-            region.srcOffset = bottom_blob.buffer_offset();
-            region.dstOffset = top_blob.buffer_offset() + dstOffset;
-            region.size = size;
+            std::vector<VkMat> bindings(2);
+            bindings[0] = bottom_blob;
+            bindings[1] = top_blob;
+
+            std::vector<vk_constant_type> constants(11);
+            constants[0].i = bottom_blob.dims;
+            constants[1].i = bottom_blob.w;
+            constants[2].i = bottom_blob.h;
+            constants[3].i = bottom_blob.c;
+            constants[4].i = bottom_blob.cstep;
+            constants[5].i = top_blob.dims;
+            constants[6].i = top_blob.w;
+            constants[7].i = top_blob.h;
+            constants[8].i = top_blob.c;
+            constants[9].i = top_blob.cstep;
+            constants[10].i = woffset;
+
+            const Pipeline* pipeline = 0;
+            if (packing == 1 && out_packing == 1)
+            {
+                pipeline = pipeline_concat;
+            }
+            else if (packing == 4 && out_packing == 4)
+            {
+                pipeline = pipeline_concat_pack4;
+            }
+            else if (packing == 4 && out_packing == 1)
+            {
+                pipeline = pipeline_concat_pack4to1;
+            }
 
-            cmd.record_prepare_transfer_barrier(bottom_blob);
-            cmd.record_copy_region(bottom_blob, top_blob, region);
+            // record
+            cmd.record_prepare_compute_barrier(bottom_blob);
+            cmd.record_pipeline(pipeline, bindings, constants, bottom_blob);
 
-            dstOffset += size;
+            woffset += bottom_blob.w * bottom_blob.packing / out_packing;
         }
 
         return 0;
@@ -312,36 +398,75 @@ int Concat::forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>&
         int w = bottom_blobs[0].w;
 
         // total height
+        size_t elemsize = bottom_blobs[0].elemsize;
+        int packing = bottom_blobs[0].packing;
         int top_h = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
-            top_h += bottom_blob.h;
+            elemsize = std::min(elemsize, bottom_blob.elemsize);
+            packing = std::min(packing, bottom_blob.packing);
+            top_h += bottom_blob.h * bottom_blob.packing;
+        }
+
+        int out_packing = top_h % 4 == 0 ? 4 : 1;
+        size_t out_elemsize = elemsize / packing * out_packing;
+
+        // TODO pack1to4 and pack4to1to4 make sense ?
+        if (packing == 1)
+        {
+            out_packing = 1;
+            out_elemsize = elemsize / packing;
         }
 
         VkMat& top_blob = top_blobs[0];
-        top_blob.create(w, top_h, elemsize, packing, opt.blob_vkallocator, opt.staging_vkallocator);
+        top_blob.create(w, top_h / out_packing, out_elemsize, out_packing, opt.blob_vkallocator, opt.staging_vkallocator);
         if (top_blob.empty())
             return -100;
 
-        cmd.record_prepare_transfer_barrier(top_blob);
+        cmd.record_prepare_compute_barrier(top_blob);
 
-        int dstOffset = 0;
+        int hoffset = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
 
-            int size = w * bottom_blob.h * bottom_blob.elemsize;
-
-            VkBufferCopy region;
-            region.srcOffset = bottom_blob.buffer_offset();
-            region.dstOffset = top_blob.buffer_offset() + dstOffset;
-            region.size = size;
+            std::vector<VkMat> bindings(2);
+            bindings[0] = bottom_blob;
+            bindings[1] = top_blob;
+
+            std::vector<vk_constant_type> constants(11);
+            constants[0].i = bottom_blob.dims;
+            constants[1].i = bottom_blob.w;
+            constants[2].i = bottom_blob.h;
+            constants[3].i = bottom_blob.c;
+            constants[4].i = bottom_blob.cstep;
+            constants[5].i = top_blob.dims;
+            constants[6].i = top_blob.w;
+            constants[7].i = top_blob.h;
+            constants[8].i = top_blob.c;
+            constants[9].i = top_blob.cstep;
+            constants[10].i = hoffset;
+
+            const Pipeline* pipeline = 0;
+            if (packing == 1 && out_packing == 1)
+            {
+                pipeline = pipeline_concat;
+            }
+            else if (packing == 4 && out_packing == 4)
+            {
+                pipeline = pipeline_concat_pack4;
+            }
+            else if (packing == 4 && out_packing == 1)
+            {
+                pipeline = pipeline_concat_pack4to1;
+            }
 
-            cmd.record_prepare_transfer_barrier(bottom_blob);
-            cmd.record_copy_region(bottom_blob, top_blob, region);
+            // record
+            cmd.record_prepare_compute_barrier(bottom_blob);
+            cmd.record_pipeline(pipeline, bindings, constants, bottom_blob);
 
-            dstOffset += size;
+            hoffset += bottom_blob.h * bottom_blob.packing / out_packing;
         }
 
         return 0;
@@ -351,6 +476,8 @@ int Concat::forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>&
     {
         // interleave image row
         int h = bottom_blobs[0].h;
+        size_t elemsize = bottom_blobs[0].elemsize;
+        int packing = bottom_blobs[0].packing;
 
         // total width
         int top_w = 0;
@@ -365,32 +492,37 @@ int Concat::forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>&
         if (top_blob.empty())
             return -100;
 
-        cmd.record_prepare_transfer_barrier(top_blob);
-
-        int dstOffset_0 = 0;
+        cmd.record_prepare_compute_barrier(top_blob);
 
+        int woffset = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
 
-            int size = bottom_blob.w * bottom_blob.elemsize;
-
-            int dstOffset = dstOffset_0;
-
-            std::vector<VkBufferCopy> regions(h);
-            for (int i=0; i<h; i++)
-            {
-                regions[i].srcOffset = bottom_blob.buffer_offset();
-                regions[i].dstOffset = top_blob.buffer_offset() + dstOffset;
-                regions[i].size = size;
-
-                dstOffset += top_blob.w * top_blob.elemsize;
-            }
-
-            cmd.record_prepare_transfer_barrier(bottom_blob);
-            cmd.record_copy_regions(bottom_blob, top_blob, regions);
-
-            dstOffset_0 += size;
+            std::vector<VkMat> bindings(2);
+            bindings[0] = bottom_blob;
+            bindings[1] = top_blob;
+
+            std::vector<vk_constant_type> constants(11);
+            constants[0].i = bottom_blob.dims;
+            constants[1].i = bottom_blob.w;
+            constants[2].i = bottom_blob.h;
+            constants[3].i = bottom_blob.c;
+            constants[4].i = bottom_blob.cstep;
+            constants[5].i = top_blob.dims;
+            constants[6].i = top_blob.w;
+            constants[7].i = top_blob.h;
+            constants[8].i = top_blob.c;
+            constants[9].i = top_blob.cstep;
+            constants[10].i = woffset;
+
+            const Pipeline* pipeline = packing == 4 ? pipeline_concat_pack4 : pipeline_concat;
+
+            // record
+            cmd.record_prepare_compute_barrier(bottom_blob);
+            cmd.record_pipeline(pipeline, bindings, constants, bottom_blob);
+
+            woffset += bottom_blob.w;
         }
 
         return 0;
@@ -403,36 +535,75 @@ int Concat::forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>&
         int h = bottom_blobs[0].h;
 
         // total channels
+        size_t elemsize = bottom_blobs[0].elemsize;
+        int packing = bottom_blobs[0].packing;
         int top_channels = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
-            top_channels += bottom_blob.c;
+            elemsize = std::min(elemsize, bottom_blob.elemsize);
+            packing = std::min(packing, bottom_blob.packing);
+            top_channels += bottom_blob.c * bottom_blob.packing;
+        }
+
+        int out_packing = top_channels % 4 == 0 ? 4 : 1;
+        size_t out_elemsize = elemsize / packing * out_packing;
+
+        // TODO pack1to4 and pack4to1to4 make sense ?
+        if (packing == 1)
+        {
+            out_packing = 1;
+            out_elemsize = elemsize / packing;
         }
 
         VkMat& top_blob = top_blobs[0];
-        top_blob.create(w, h, top_channels, elemsize, packing, opt.blob_vkallocator, opt.staging_vkallocator);
+        top_blob.create(w, h, top_channels / out_packing, out_elemsize, out_packing, opt.blob_vkallocator, opt.staging_vkallocator);
         if (top_blob.empty())
             return -100;
 
-        cmd.record_prepare_transfer_barrier(top_blob);
+        cmd.record_prepare_compute_barrier(top_blob);
 
-        int dstOffset = 0;
+        int coffset = 0;
         for (size_t b=0; b<bottom_blobs.size(); b++)
         {
             const VkMat& bottom_blob = bottom_blobs[b];
 
-            int size = bottom_blob.total() * bottom_blob.elemsize;
-
-            VkBufferCopy region;
-            region.srcOffset = bottom_blob.buffer_offset();
-            region.dstOffset = top_blob.buffer_offset() + dstOffset;
-            region.size = size;
+            std::vector<VkMat> bindings(2);
+            bindings[0] = bottom_blob;
+            bindings[1] = top_blob;
+
+            std::vector<vk_constant_type> constants(11);
+            constants[0].i = bottom_blob.dims;
+            constants[1].i = bottom_blob.w;
+            constants[2].i = bottom_blob.h;
+            constants[3].i = bottom_blob.c;
+            constants[4].i = bottom_blob.cstep;
+            constants[5].i = top_blob.dims;
+            constants[6].i = top_blob.w;
+            constants[7].i = top_blob.h;
+            constants[8].i = top_blob.c;
+            constants[9].i = top_blob.cstep;
+            constants[10].i = coffset;
+
+            const Pipeline* pipeline = 0;
+            if (packing == 1 && out_packing == 1)
+            {
+                pipeline = pipeline_concat;
+            }
+            else if (packing == 4 && out_packing == 4)
+            {
+                pipeline = pipeline_concat_pack4;
+            }
+            else if (packing == 4 && out_packing == 1)
+            {
+                pipeline = pipeline_concat_pack4to1;
+            }
 
-            cmd.record_prepare_transfer_barrier(bottom_blob);
-            cmd.record_copy_region(bottom_blob, top_blob, region);
+            // record
+            cmd.record_prepare_compute_barrier(bottom_blob);
+            cmd.record_pipeline(pipeline, bindings, constants, bottom_blob);
 
-            dstOffset += size;
+            coffset += bottom_blob.c * bottom_blob.packing / out_packing;
         }
 
         return 0;
@@ -440,12 +611,116 @@ int Concat::forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>&
 
     if (dims == 3 && axis == 1)
     {
-        // TODO
+        // interleave dim height
+        int w = bottom_blobs[0].w;
+        int channels = bottom_blobs[0].c;
+        size_t elemsize = bottom_blobs[0].elemsize;
+        int packing = bottom_blobs[0].packing;
+
+        // total height
+        int top_h = 0;
+        for (size_t b=0; b<bottom_blobs.size(); b++)
+        {
+            const VkMat& bottom_blob = bottom_blobs[b];
+            top_h += bottom_blob.h;
+        }
+
+        VkMat& top_blob = top_blobs[0];
+        top_blob.create(w, top_h, channels, elemsize, packing, opt.blob_vkallocator, opt.staging_vkallocator);
+        if (top_blob.empty())
+            return -100;
+
+        cmd.record_prepare_compute_barrier(top_blob);
+
+        int hoffset = 0;
+        for (size_t b=0; b<bottom_blobs.size(); b++)
+        {
+            const VkMat& bottom_blob = bottom_blobs[b];
+
+            std::vector<VkMat> bindings(2);
+            bindings[0] = bottom_blob;
+            bindings[1] = top_blob;
+
+            std::vector<vk_constant_type> constants(11);
+            constants[0].i = bottom_blob.dims;
+            constants[1].i = bottom_blob.w;
+            constants[2].i = bottom_blob.h;
+            constants[3].i = bottom_blob.c;
+            constants[4].i = bottom_blob.cstep;
+            constants[5].i = top_blob.dims;
+            constants[6].i = top_blob.w;
+            constants[7].i = top_blob.h;
+            constants[8].i = top_blob.c;
+            constants[9].i = top_blob.cstep;
+            constants[10].i = hoffset;
+
+            const Pipeline* pipeline = packing == 4 ? pipeline_concat_pack4 : pipeline_concat;
+
+            // record
+            cmd.record_prepare_compute_barrier(bottom_blob);
+            cmd.record_pipeline(pipeline, bindings, constants, bottom_blob);
+
+            hoffset += bottom_blob.h;
+        }
+
+        return 0;
     }
 
     if (dims == 3 && axis == 2)
     {
-        // TODO
+        // interleave dim width
+        int h = bottom_blobs[0].h;
+        int channels = bottom_blobs[0].c;
+        size_t elemsize = bottom_blobs[0].elemsize;
+        int packing = bottom_blobs[0].packing;
+
+        // total height
+        int top_w = 0;
+        for (size_t b=0; b<bottom_blobs.size(); b++)
+        {
+            const VkMat& bottom_blob = bottom_blobs[b];
+            top_w += bottom_blob.w;
+        }
+
+        VkMat& top_blob = top_blobs[0];
+        top_blob.create(top_w, h, channels, elemsize, packing, opt.blob_vkallocator, opt.staging_vkallocator);
+        if (top_blob.empty())
+            return -100;
+
+        cmd.record_prepare_compute_barrier(top_blob);
+
+        int woffset = 0;
+        for (size_t b=0; b<bottom_blobs.size(); b++)
+        {
+            const VkMat& bottom_blob = bottom_blobs[b];
+
+            std::vector<VkMat> bindings(2);
+            bindings[0] = bottom_blob;
+            bindings[1] = top_blob;
+
+            std::vector<vk_constant_type> constants(11);
+            constants[0].i = bottom_blob.dims;
+            constants[1].i = bottom_blob.w;
+            constants[2].i = bottom_blob.h;
+            constants[3].i = bottom_blob.c;
+            constants[4].i = bottom_blob.cstep;
+            constants[5].i = top_blob.dims;
+            constants[6].i = top_blob.w;
+            constants[7].i = top_blob.h;
+            constants[8].i = top_blob.c;
+            constants[9].i = top_blob.cstep;
+            constants[10].i = woffset;
+
+            const Pipeline* pipeline = packing == 4 ? pipeline_concat_pack4 : pipeline_concat;
+
+            // record
+            cmd.record_prepare_compute_barrier(bottom_blob);
+            cmd.record_pipeline(pipeline, bindings, constants, bottom_blob);
+
+            woffset += bottom_blob.w;
+        }
+
+        return 0;
     }
 
     return 0;
diff --git a/src/layer/concat.h b/src/layer/concat.h
index 2d90ba14a..31ce72382 100644
--- a/src/layer/concat.h
+++ b/src/layer/concat.h
@@ -29,11 +29,21 @@ public:
     virtual int forward(const std::vector<Mat>& bottom_blobs, std::vector<Mat>& top_blobs, const Option& opt) const;
 
 #if NCNN_VULKAN
+    virtual int create_pipeline();
+    virtual int destroy_pipeline();
+
     virtual int forward(const std::vector<VkMat>& bottom_blobs, std::vector<VkMat>& top_blobs, VkCompute& cmd, const Option& opt) const;
 #endif // NCNN_VULKAN
 
 public:
     int axis;
+
+#if NCNN_VULKAN
+    Pipeline* pipeline_concat;
+    Pipeline* pipeline_concat_pack4;
+    Pipeline* pipeline_concat_pack4to1;
+#endif // NCNN_VULKAN
+
 };
 
 } // namespace ncnn
diff --git a/src/layer/shader/concat.comp b/src/layer/shader/concat.comp
new file mode 100644
index 000000000..389c68999
--- /dev/null
+++ b/src/layer/shader/concat.comp
@@ -0,0 +1,87 @@
+// Tencent is pleased to support the open source community by making ncnn available.
+//
+// Copyright (C) 2019 THL A29 Limited, a Tencent company. All rights reserved.
+//
+// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// https://opensource.org/licenses/BSD-3-Clause
+//
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+#version 450
+
+layout (constant_id = 0) const int axis = 0;
+
+layout (local_size_x_id = 233) in;
+layout (local_size_y_id = 234) in;
+layout (local_size_z_id = 235) in;
+
+layout (binding = 0) readonly buffer bottom_blob { float bottom_blob_data[]; };
+layout (binding = 1) writeonly buffer top_blob { float top_blob_data[]; };
+
+layout (push_constant) uniform parameter
+{
+    int dims;
+    int w;
+    int h;
+    int c;
+    int cstep;
+
+    int outdims;
+    int outw;
+    int outh;
+    int outc;
+    int outcstep;
+
+    int offset;
+} p;
+
+void main()
+{
+    int gx = int(gl_GlobalInvocationID.x);
+    int gy = int(gl_GlobalInvocationID.y);
+    int gz = int(gl_GlobalInvocationID.z);
+
+    if (gx >= p.w || gy >= p.h || gz >= p.c)
+        return;
+
+    int v_offset;
+    float v;
+
+    if (p.dims == 1) // axis == 0
+    {
+        v_offset = gx + p.offset;
+        v = bottom_blob_data[gx];
+    }
+    else if (p.dims == 2 && axis == 0)
+    {
+        v_offset = (gy + p.offset) * p.outw + gx;
+        v = bottom_blob_data[gy * p.w + gx];
+    }
+    else if (p.dims == 2 && axis == 1)
+    {
+        v_offset = gy * p.outw + gx + p.offset;
+        v = bottom_blob_data[gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 0)
+    {
+        v_offset = (gz + p.offset) * p.outcstep + gy * p.outw + gx;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 1)
+    {
+        v_offset = gz * p.outcstep + (gy + p.offset) * p.outw + gx;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 2)
+    {
+        v_offset = gz * p.outcstep + gy * p.outw + gx + p.offset;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+
+    top_blob_data[v_offset] = v;
+}
diff --git a/src/layer/shader/concat_pack4.comp b/src/layer/shader/concat_pack4.comp
new file mode 100644
index 000000000..121fe50b8
--- /dev/null
+++ b/src/layer/shader/concat_pack4.comp
@@ -0,0 +1,87 @@
+// Tencent is pleased to support the open source community by making ncnn available.
+//
+// Copyright (C) 2019 THL A29 Limited, a Tencent company. All rights reserved.
+//
+// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// https://opensource.org/licenses/BSD-3-Clause
+//
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+#version 450
+
+layout (constant_id = 0) const int axis = 0;
+
+layout (local_size_x_id = 233) in;
+layout (local_size_y_id = 234) in;
+layout (local_size_z_id = 235) in;
+
+layout (binding = 0) readonly buffer bottom_blob { vec4 bottom_blob_data[]; };
+layout (binding = 1) writeonly buffer top_blob { vec4 top_blob_data[]; };
+
+layout (push_constant) uniform parameter
+{
+    int dims;
+    int w;
+    int h;
+    int c;
+    int cstep;
+
+    int outdims;
+    int outw;
+    int outh;
+    int outc;
+    int outcstep;
+
+    int offset;
+} p;
+
+void main()
+{
+    int gx = int(gl_GlobalInvocationID.x);
+    int gy = int(gl_GlobalInvocationID.y);
+    int gz = int(gl_GlobalInvocationID.z);
+
+    if (gx >= p.w || gy >= p.h || gz >= p.c)
+        return;
+
+    int v_offset;
+    vec4 v;
+
+    if (p.dims == 1) // axis == 0
+    {
+        v_offset = gx + p.offset;
+        v = bottom_blob_data[gx];
+    }
+    else if (p.dims == 2 && axis == 0)
+    {
+        v_offset = (gy + p.offset) * p.outw + gx;
+        v = bottom_blob_data[gy * p.w + gx];
+    }
+    else if (p.dims == 2 && axis == 1)
+    {
+        v_offset = gy * p.outw + gx + p.offset;
+        v = bottom_blob_data[gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 0)
+    {
+        v_offset = (gz + p.offset) * p.outcstep + gy * p.outw + gx;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 1)
+    {
+        v_offset = gz * p.outcstep + (gy + p.offset) * p.outw + gx;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 2)
+    {
+        v_offset = gz * p.outcstep + gy * p.outw + gx + p.offset;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+
+    top_blob_data[v_offset] = v;
+}
diff --git a/src/layer/shader/concat_pack4to1.comp b/src/layer/shader/concat_pack4to1.comp
new file mode 100644
index 000000000..6fc6062a0
--- /dev/null
+++ b/src/layer/shader/concat_pack4to1.comp
@@ -0,0 +1,90 @@
+// Tencent is pleased to support the open source community by making ncnn available.
+//
+// Copyright (C) 2019 THL A29 Limited, a Tencent company. All rights reserved.
+//
+// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// https://opensource.org/licenses/BSD-3-Clause
+//
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+#version 450
+
+layout (constant_id = 0) const int axis = 0;
+
+layout (local_size_x_id = 233) in;
+layout (local_size_y_id = 234) in;
+layout (local_size_z_id = 235) in;
+
+layout (binding = 0) readonly buffer bottom_blob { vec4 bottom_blob_data[]; };
+layout (binding = 1) writeonly buffer top_blob { float top_blob_data[]; };
+
+layout (push_constant) uniform parameter
+{
+    int dims;
+    int w;
+    int h;
+    int c;
+    int cstep;
+
+    int outdims;
+    int outw;
+    int outh;
+    int outc;
+    int outcstep;
+
+    int offset;
+} p;
+
+void main()
+{
+    int gx = int(gl_GlobalInvocationID.x);
+    int gy = int(gl_GlobalInvocationID.y);
+    int gz = int(gl_GlobalInvocationID.z);
+
+    if (gx >= p.w || gy >= p.h || gz >= p.c)
+        return;
+
+    ivec4 v_offset;
+    vec4 v;
+
+    if (p.dims == 1) // axis == 0
+    {
+        v_offset = ivec4(gx * 4 + p.offset) + ivec4(0, 1, 2, 3);
+        v = bottom_blob_data[gx];
+    }
+    else if (p.dims == 2 && axis == 0)
+    {
+        v_offset = (ivec4(gx * 4 + p.offset) + ivec4(0, 1, 2, 3)) * p.outw + gx;
+        v = bottom_blob_data[gy * p.w + gx];
+    }
+    else if (p.dims == 2 && axis == 1)
+    {
+        v_offset = (ivec4(gx * 4) + ivec4(0, 1, 2, 3)) * p.outw + gx + p.offset;
+        v = bottom_blob_data[gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 0)
+    {
+        v_offset = (ivec4(gz * 4 + p.offset) + ivec4(0, 1, 2, 3)) * p.outcstep + gy * p.outw + gx;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 1)
+    {
+        v_offset = (ivec4(gz * 4) + ivec4(0, 1, 2, 3)) * p.outcstep + (gy + p.offset) * p.outw + gx;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+    else if (p.dims == 3 && axis == 2)
+    {
+        v_offset = (ivec4(gz * 4) + ivec4(0, 1, 2, 3)) * p.outcstep + gy * p.outw + gx + p.offset;
+        v = bottom_blob_data[gz * p.cstep + gy * p.w + gx];
+    }
+
+    top_blob_data[v_offset.r] = v.r;
+    top_blob_data[v_offset.g] = v.g;
+    top_blob_data[v_offset.b] = v.b;
+    top_blob_data[v_offset.a] = v.a;
+}