diff --git a/modules/auth/wechat/client.go b/modules/auth/wechat/client.go
index bb1772b2b..6734977a1 100644
--- a/modules/auth/wechat/client.go
+++ b/modules/auth/wechat/client.go
@@ -62,6 +62,7 @@ func getWechatRestyClient() *resty.Client {
 	return client
 }
 
+// api doc:https://developers.weixin.qq.com/doc/offiaccount/Basic_Information/Get_access_token.html
 func callAccessToken() *AccessTokenResponse {
 	client := getWechatRestyClient()
 
@@ -79,6 +80,8 @@ func callAccessToken() *AccessTokenResponse {
 	return &result
 }
 
+//callQRCodeCreate  call the wechat api to create qr-code,
+// api doc: https://developers.weixin.qq.com/doc/offiaccount/Account_Management/Generating_a_Parametric_QR_Code.html
 func callQRCodeCreate(sceneStr string) (*QRCodeResponse, bool) {
 	client := getWechatRestyClient()
 
diff --git a/modules/auth/wechat/event_handle.go b/modules/auth/wechat/event_handle.go
index c49c6d763..b40ab3101 100644
--- a/modules/auth/wechat/event_handle.go
+++ b/modules/auth/wechat/event_handle.go
@@ -37,6 +37,15 @@ type EventReply struct {
 	Content      string
 }
 
+const (
+	WECHAT_EVENT_SUBSCRIBE = "subscribe"
+	WECHAT_EVENT_SCAN      = "SCAN"
+)
+
+const (
+	WECHAT_MSG_TYPE_TEXT = "text"
+)
+
 func HandleSubscribeEvent(we WechatEvent) string {
 	eventKey := we.EventKey
 	if eventKey == "" {
diff --git a/modules/auth/wechat/qr_code.go b/modules/auth/wechat/qr_code.go
index 5506cecb7..8c2da55c9 100644
--- a/modules/auth/wechat/qr_code.go
+++ b/modules/auth/wechat/qr_code.go
@@ -1,8 +1,11 @@
 package wechat
 
+import "code.gitea.io/gitea/modules/log"
+
 func GetWechatQRCode4Bind(sceneStr string) *QRCodeResponse {
 	result, retryFlag := callQRCodeCreate(sceneStr)
 	if retryFlag {
+		log.Info("retry wechat qr-code calling,sceneStr=%s", sceneStr)
 		refreshAccessTokenCache()
 		result, _ = callQRCodeCreate(sceneStr)
 	}
diff --git a/routers/authentication/wechat.go b/routers/authentication/wechat.go
index 866825fce..7a62850e2 100644
--- a/routers/authentication/wechat.go
+++ b/routers/authentication/wechat.go
@@ -43,7 +43,7 @@ func GetQRCode4Bind(ctx *context.Context) {
 	})
 }
 
-// GetBindStatus
+// GetBindStatus   the web page will poll the service to get bind status
 func GetBindStatus(ctx *context.Context) {
 	sceneStr := ctx.Query("sceneStr")
 	val, _ := redis_client.Get(redis_key.WechatBindingUserIdKey(sceneStr))
@@ -86,6 +86,7 @@ func GetBindPage(ctx *context.Context) {
 }
 
 func createQRCode4Bind(userId int64) (*QRCodeResponse, error) {
+	log.Info("start to create qr-code for binding.userId=%d", userId)
 	sceneStr := gouuid.NewV4().String()
 	r := wechat.GetWechatQRCode4Bind(sceneStr)
 	if r == nil {
@@ -98,7 +99,7 @@ func createQRCode4Bind(userId int64) (*QRCodeResponse, error) {
 	})
 	isOk, err := redis_client.Setex(redis_key.WechatBindingUserIdKey(sceneStr), string(jsonStr), time.Duration(setting.WechatQRCodeExpireSeconds)*time.Second)
 	if err != nil {
-		log.Error("createQRCode4Bind failed.e=%v", err)
+		log.Error("createQRCode4Bind failed.e=%+v", err)
 		return nil, err
 	}
 	if !isOk {
diff --git a/routers/authentication/wechat_event.go b/routers/authentication/wechat_event.go
index 35ba23166..9b1cebec6 100644
--- a/routers/authentication/wechat_event.go
+++ b/routers/authentication/wechat_event.go
@@ -10,6 +10,8 @@ import (
 )
 
 // AcceptWechatEvent
+// https://developers.weixin.qq.com/doc/offiaccount/Message_Management/Receiving_event_pushes.html
+// https://developers.weixin.qq.com/doc/offiaccount/Message_Management/Passive_user_reply_message.html
 func AcceptWechatEvent(ctx *context.Context) {
 	b, _ := ioutil.ReadAll(ctx.Req.Request.Body)
 	we := wechat.WechatEvent{}
@@ -17,8 +19,10 @@ func AcceptWechatEvent(ctx *context.Context) {
 
 	log.Info("accept wechat event= %+v", we)
 	var replyStr string
-	if we.Event == "subscribe" {
+	switch we.Event {
+	case wechat.WECHAT_EVENT_SUBSCRIBE, wechat.WECHAT_EVENT_SCAN:
 		replyStr = wechat.HandleSubscribeEvent(we)
+		break
 	}
 
 	if replyStr == "" {
@@ -29,7 +33,7 @@ func AcceptWechatEvent(ctx *context.Context) {
 		ToUserName:   we.FromUserName,
 		FromUserName: we.ToUserName,
 		CreateTime:   time.Now().Unix(),
-		MsgType:      "text",
+		MsgType:      wechat.WECHAT_MSG_TYPE_TEXT,
 		Content:      replyStr,
 	}
 	ctx.XML(200, reply)