diff --git a/parser/onnx/onnx_parser.cc b/parser/onnx/onnx_parser.cc
index 0f88ab3..dc5bf09 100644
--- a/parser/onnx/onnx_parser.cc
+++ b/parser/onnx/onnx_parser.cc
@@ -671,13 +671,12 @@ Status OnnxModelParser::ParseAllNodeProto(ge::onnx::GraphProto &onnx_graph, ge::
 }
 
 Status OnnxModelParser::GetGraphInputs(ge::onnx::GraphProto &onnx_graph, std::vector<ge::Operator> &input_ops) {
-  if (input_node_names_.empty()) {
-    // subgraph might not have input, we use constant nodes as the start nodes of graph
-    for (int i = 0; i < onnx_graph.node_size(); i++) {
-      ge::onnx::NodeProto *node = onnx_graph.mutable_node(i);
-      if (node->op_type() == kOpTypeConstant) {
-        input_node_names_.emplace_back(node->name());
-      }
+  // subgraph might not have input, or isolated const nodes exist in the graph,
+  // we use constant nodes as the start nodes of graph
+  for (int i = 0; i < onnx_graph.node_size(); i++) {
+    ge::onnx::NodeProto *node = onnx_graph.mutable_node(i);
+    if (node->op_type() == kOpTypeConstant) {
+      input_node_names_.emplace_back(node->name());
     }
   }
   for (auto in_name : input_node_names_) {