diff --git a/packageC/pages/presell/cart/cart.js b/packageC/pages/presell/cart/cart.js
index c439edf..2b3e327 100644
--- a/packageC/pages/presell/cart/cart.js
+++ b/packageC/pages/presell/cart/cart.js
@@ -656,7 +656,7 @@ Page({
                 })
             }else{
                 th.setData({quan_price:0});
-                if(th.data.using_quan[bn_pick].isby==1){
+                if(th.data.using_quan && th.data.using_quan[bn_pick] && th.data.using_quan[bn_pick].isby==1){
                     var txt="using_quan["+bn_pick+"]";
                     th.setData({[txt]:{}});
                 }