diff --git a/controllers/knowledge_upload_controller.go b/controllers/knowledge_upload_controller.go
index 747041681..142d00263 100644
--- a/controllers/knowledge_upload_controller.go
+++ b/controllers/knowledge_upload_controller.go
@@ -15,7 +15,7 @@ type KnowUploadController struct {
 func (c *KnowUploadController) SnsUploadImg() {
 	callResult := &CallResult{}
 	var files []*multipart.FileHeader
-	if c.Ctx.Request.MultipartForm != nil {
+	if len(c.Ctx.Request.MultipartForm.File) > 0 {
 		files = c.Ctx.Request.MultipartForm.File["userfiles"]
 	}
 	isThumb, _ := c.GetBool("isThumb")