diff --git a/platformapi/alipayapi/pay_for_user.go b/platformapi/alipayapi/pay_for_user.go
index 7042604c..5a3229a9 100644
--- a/platformapi/alipayapi/pay_for_user.go
+++ b/platformapi/alipayapi/pay_for_user.go
@@ -8,7 +8,6 @@ import (
 	"errors"
 	"fmt"
 	"git.rosy.net.cn/baseapi/utils"
-	"git.rosy.net.cn/gopay-main/pkg/util"
 	"io/ioutil"
 	"strings"
 )
@@ -127,19 +126,19 @@ func GetCertSN(certPathOrData interface{}) (sn string, err error) {
 	case string:
 		certData, err = ioutil.ReadFile(pathOrData)
 		if err != nil {
-			return util.NULL, err
+			return "", err
 		}
 	case []byte:
 		certData = pathOrData
 	default:
-		return util.NULL, errors.New("certPathOrData 证书类型断言错误")
+		return "", errors.New("certPathOrData 证书类型断言错误")
 	}
 
 	block, _ := pem.Decode(certData)
 	if block != nil {
 		cert, err := x509.ParseCertificate(block.Bytes)
 		if err != nil {
-			return util.NULL, err
+			return "", err
 		}
 		name := cert.Issuer.String()
 		serialNumber := cert.SerialNumber.String()
@@ -148,8 +147,8 @@ func GetCertSN(certPathOrData interface{}) (sn string, err error) {
 		h.Write([]byte(serialNumber))
 		sn = hex.EncodeToString(h.Sum(nil))
 	}
-	if sn == util.NULL {
-		return util.NULL, errors.New("failed to get sn,please check your cert")
+	if sn == "" {
+		return "", errors.New("failed to get sn,please check your cert")
 	}
 	return sn, nil
 }
@@ -180,12 +179,12 @@ func GetRootCertSN(rootCertPathOrData interface{}) (sn string, err error) {
 	case string:
 		certData, err = ioutil.ReadFile(pathOrData)
 		if err != nil {
-			return util.NULL, err
+			return "", err
 		}
 	case []byte:
 		certData = pathOrData
 	default:
-		return util.NULL, errors.New("rootCertPathOrData 断言异常")
+		return "", errors.New("rootCertPathOrData 断言异常")
 	}
 
 	pems := strings.Split(string(certData), certEnd)
@@ -203,15 +202,15 @@ func GetRootCertSN(rootCertPathOrData interface{}) (sn string, err error) {
 			h := md5.New()
 			h.Write([]byte(name))
 			h.Write([]byte(serialNumber))
-			if sn == util.NULL {
+			if sn == "" {
 				sn += hex.EncodeToString(h.Sum(nil))
 			} else {
 				sn += "_" + hex.EncodeToString(h.Sum(nil))
 			}
 		}
 	}
-	if sn == util.NULL {
-		return util.NULL, errors.New("failed to get sn,please check your cert")
+	if sn == "" {
+		return "", errors.New("failed to get sn,please check your cert")
 	}
 	return sn, nil
 }