diff --git a/lib/middleware.js b/lib/middleware.js
index 112d4fd..855bc3f 100644
--- a/lib/middleware.js
+++ b/lib/middleware.js
@@ -48,6 +48,9 @@ Basic.prototype.done = function (handler) {
   var self = this;
   var payment = self.payment;
   return function (req, res, next) {
+    if(req.wxpayconfig){
+      payment = new Payment(req.wxpayconfig);
+    }
     if (req.method !== 'POST') {
       var error = new Error();
       error.name = 'NotImplemented';
@@ -131,6 +134,10 @@ Refund.prototype.done = function (handler) {
   var key = self.key;
 
   return function (req, res, next) {
+    if(req.wxpayconfig){
+      payment = new Payment(req.wxpayconfig);
+      key = md5(req.wxpayconfig.partnerKey).toLowerCase();
+    }
     if (req.method !== 'POST') {
       var error = new Error();
       error.name = 'NotImplemented';