diff --git a/sheep/helper/tools.js b/sheep/helper/tools.js
index 49efcecb..8712917e 100644
--- a/sheep/helper/tools.js
+++ b/sheep/helper/tools.js
@@ -19,15 +19,19 @@ export default {
    * @param {String} url -图片地址
    */
   checkMPUrl(url) {
+    if (!url || typeof url !== 'string') {
+      return url;
+    }
+
     // #ifdef MP
     if (
-      url.substring(0, 4) === 'http' &&
-      url.substring(0, 5) !== 'https' &&
-      url.substring(0, 12) !== 'http://store' &&
-      url.substring(0, 10) !== 'http://tmp' &&
-      url.substring(0, 10) !== 'http://usr'
+      url.startsWith('http://') &&
+      !url.startsWith('https://') &&
+      !url.startsWith('http://store') &&
+      !url.startsWith('http://tmp') &&
+      !url.startsWith('http://usr')
     ) {
-      url = 'https' + url.substring(4, url.length);
+      url = url.replace('http://', 'https://');
     }
     // #endif
     return url;