diff --git a/dctw/v1/api/card/card_test.go b/dctw/v1/api/card/card_test.go
index ed8a3da..83d9440 100644
--- a/dctw/v1/api/card/card_test.go
+++ b/dctw/v1/api/card/card_test.go
@@ -26,7 +26,7 @@ func TestCard_Order(t *testing.T) {
 	req := &Order{
 		Number:     1,
 		MerchantId: "23329",
-		OutTradeNo: "test_1_zltx_4",
+		OutTradeNo: "test_card_zltx_1",
 		ProductId:  "222",
 		Mobile:     "18666666666",
 		NotifyUrl:  "http://test.openapi.1688sup.cn",
@@ -56,7 +56,7 @@ func TestCard_Query(t *testing.T) {
 	a := &Card{DctWServer: server}
 	req := &Query{
 		MerchantId: "23329",
-		OutTradeNo: "test_1_zltx_4",
+		OutTradeNo: "test_card_zltx_1",
 		Version:    "1.0",
 	}
 	resp, err := a.Query(context.Background(), req)
diff --git a/dctw/v1/api/direct/direct_test.go b/dctw/v1/api/direct/direct_test.go
index 210aca5..347ed88 100644
--- a/dctw/v1/api/direct/direct_test.go
+++ b/dctw/v1/api/direct/direct_test.go
@@ -26,7 +26,7 @@ func TestDirect_Order(t *testing.T) {
 	req := &Order{
 		Number:          1,
 		MerchantId:      "23329",
-		OutTradeNo:      "test_1_zltx_7",
+		OutTradeNo:      "test_direct_zltx_7",
 		ProductId:       "106",
 		AccountType:     1,
 		RechargeAccount: "18666666666",
@@ -57,7 +57,7 @@ func TestDirect_Query(t *testing.T) {
 	a := &Direct{DctWServer: server}
 	req := &Query{
 		MerchantId: "23329",
-		OutTradeNo: "test_1_zltx_7",
+		OutTradeNo: "test_direct_zltx_7",
 		Version:    "1.0",
 	}
 	resp, err := a.Query(context.Background(), req)
diff --git a/dctw/v1/core/core.go b/dctw/v1/core/core.go
index b3ddceb..a2206ad 100644
--- a/dctw/v1/core/core.go
+++ b/dctw/v1/core/core.go
@@ -14,7 +14,7 @@ import (
 
 const (
 	DeBug           = true
-	SignType        = "MD5"
+	SignType        = "md5"
 	SignKeyName     = "Authorization"
 	ApplicationJSON = "application/json"
 )
@@ -82,7 +82,7 @@ func NewDctWServer(config *DctWConfig, o ...Option) (*DctWServer, error) {
 
 func (c *DctWServer) Sign(body, path, timestamp string) string {
 	str := c.Config.AppId + body + path + timestamp + c.Config.AppKey
-	return utils.Md5([]byte(str))
+	return utils.Md5ToLower([]byte(str))
 }
 
 func (c *DctWServer) BuildAuth(signStr, timestamp string) string {
diff --git a/utils/utils.go b/utils/utils.go
index 40d7670..80f6e7f 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -29,6 +29,11 @@ func Load(dir string) ([]string, error) {
 	return files, nil
 }
 
+func Md5ToLower(values []byte) string {
+	hash := md5.Sum(values)
+	return strings.ToLower(hex.EncodeToString(hash[:]))
+}
+
 func Md5(values []byte) string {
 	hash := md5.Sum(values)
 	return strings.ToUpper(hex.EncodeToString(hash[:]))