diff --git a/webapp/controller/PayController.class.php b/webapp/controller/PayController.class.php
index c5f6e80..4d0db00 100644
--- a/webapp/controller/PayController.class.php
+++ b/webapp/controller/PayController.class.php
@@ -135,7 +135,7 @@ class PayController {
             echo json_encode(array(
                 'errcode' => 0,
                 'errmsg' => '',
-                'pay_str' => $xmlobj->PayStr
+                'pay_str' => (string)$xmlobj->PayStr
             ));
             die();
         } else {