diff --git a/demo/js/qiniu.js b/demo/js/qiniu.js
index f84dc38b..70142b13 100644
--- a/demo/js/qiniu.js
+++ b/demo/js/qiniu.js
@@ -249,7 +249,7 @@ function QiniuJsSDK() {
         }
 
 
-        var token = '';
+        that.token = '';
         var ctx = '';
 
         plupload.extend(option, op, {
@@ -260,17 +260,22 @@ function QiniuJsSDK() {
         });
 
         var uploader = new plupload.Uploader(option);
+
         var getUpToken = function() {
-            var ajax = that.createAjax();
-            ajax.open('GET', uptoken_url, true);
-            ajax.setRequestHeader("If-Modified-Since", "0");
-            ajax.onreadystatechange = function() {
-                if (ajax.readyState === 4 && ajax.status === 200) {
-                    var res = that.parseJSON(ajax.responseText);
-                    token = res.uptoken;
-                }
-            };
-            ajax.send();
+            if (!op.uptoken) {
+                var ajax = that.createAjax();
+                ajax.open('GET', uptoken_url, true);
+                ajax.setRequestHeader("If-Modified-Since", "0");
+                ajax.onreadystatechange = function() {
+                    if (ajax.readyState === 4 && ajax.status === 200) {
+                        var res = that.parseJSON(ajax.responseText);
+                        that.token = res.uptoken;
+                    }
+                };
+                ajax.send();
+            } else {
+                that.token = op.uptoken;
+            }
         };
 
         uploader.bind('Init', function(up, params) {
@@ -297,7 +302,7 @@ function QiniuJsSDK() {
                     'multipart': true,
                     'chunk_size': undefined,
                     'multipart_params': {
-                        'token': token,
+                        'token': that.token,
                         'key': file.name
                     }
                 });
@@ -315,7 +320,7 @@ function QiniuJsSDK() {
                         'multipart': false,
                         'chunk_size': chunk_size,
                         'headers': {
-                            'Authorization': 'UpToken ' + token
+                            'Authorization': 'UpToken ' + that.token
                         },
                         'multipart_params': {}
                     });
@@ -426,7 +431,7 @@ function QiniuJsSDK() {
                     var ajax = that.createAjax();
                     ajax.open('POST', url, true);
                     ajax.setRequestHeader('Content-Type', 'text/plain;charset=UTF-8');
-                    ajax.setRequestHeader('Authorization', 'UpToken ' + token);
+                    ajax.setRequestHeader('Authorization', 'UpToken ' + that.token);
                     ajax.send(ctx);
                     ajax.onreadystatechange = function() {
                         if (ajax.readyState === 4) {
diff --git a/src/qiniu.js b/src/qiniu.js
index b41ec769..70142b13 100644
--- a/src/qiniu.js
+++ b/src/qiniu.js
@@ -249,7 +249,7 @@ function QiniuJsSDK() {
         }
 
 
-        var token = '';
+        that.token = '';
         var ctx = '';
 
         plupload.extend(option, op, {
@@ -260,17 +260,22 @@ function QiniuJsSDK() {
         });
 
         var uploader = new plupload.Uploader(option);
+
         var getUpToken = function() {
-            var ajax = that.createAjax();
-            ajax.open('GET', uptoken_url, true);
-            ajax.setRequestHeader("If-Modified-Since", "0");
-            ajax.onreadystatechange = function() {
-                if (ajax.readyState === 4 && ajax.status === 200) {
-                    var res = that.parseJSON(ajax.responseText);
-                    token = res.uptoken;
-                }
-            };
-            ajax.send();
+            if (!op.uptoken) {
+                var ajax = that.createAjax();
+                ajax.open('GET', uptoken_url, true);
+                ajax.setRequestHeader("If-Modified-Since", "0");
+                ajax.onreadystatechange = function() {
+                    if (ajax.readyState === 4 && ajax.status === 200) {
+                        var res = that.parseJSON(ajax.responseText);
+                        that.token = res.uptoken;
+                    }
+                };
+                ajax.send();
+            } else {
+                that.token = op.uptoken;
+            }
         };
 
         uploader.bind('Init', function(up, params) {
@@ -297,7 +302,7 @@ function QiniuJsSDK() {
                     'multipart': true,
                     'chunk_size': undefined,
                     'multipart_params': {
-                        'token': token,
+                        'token': that.token,
                         'key': file.name
                     }
                 });
@@ -315,7 +320,7 @@ function QiniuJsSDK() {
                         'multipart': false,
                         'chunk_size': chunk_size,
                         'headers': {
-                            'Authorization': 'UpToken ' + token
+                            'Authorization': 'UpToken ' + that.token
                         },
                         'multipart_params': {}
                     });
@@ -355,6 +360,8 @@ function QiniuJsSDK() {
                             errTip = '文件验证失败。请稍后重试。';
                             break;
                         case plupload.HTTP_ERROR:
+                            var errorObj = that.parseJSON(err.response);
+                            var errorText = errorObj.error;
                             switch (err.status) {
                                 case 400:
                                     errTip = "请求报文格式错误。";
@@ -373,6 +380,8 @@ function QiniuJsSDK() {
                                     break;
                                 case 614:
                                     errTip = "文件已存在。";
+                                    errorObj = that.parseJSON(errorObj.error);
+                                    errorText = errorObj.error || 'file exists';
                                     break;
                                 case 631:
                                     errTip = "指定空间不存在。";
@@ -384,8 +393,7 @@ function QiniuJsSDK() {
                                     errTip = "未知错误。";
                                     break;
                             }
-                            var errorObj = that.parseJSON(err.response);
-                            errTip = errTip + '(' + err.status + '：' + errorObj.error + ')';
+                            errTip = errTip + '(' + err.status + '：' + errorText + ')';
                             break;
                         case plupload.SECURITY_ERROR:
                             errTip = '安全配置错误。请联系网站管理员。';
@@ -407,6 +415,8 @@ function QiniuJsSDK() {
                     if (Error_Handler) {
                         Error_Handler(up, err, errTip);
                     }
+                } else {
+
                 }
                 up.refresh(); // Reposition Flash/Silverlight
             };
@@ -421,13 +431,22 @@ function QiniuJsSDK() {
                     var ajax = that.createAjax();
                     ajax.open('POST', url, true);
                     ajax.setRequestHeader('Content-Type', 'text/plain;charset=UTF-8');
-                    ajax.setRequestHeader('Authorization', 'UpToken ' + token);
+                    ajax.setRequestHeader('Authorization', 'UpToken ' + that.token);
                     ajax.send(ctx);
                     ajax.onreadystatechange = function() {
-                        if (ajax.readyState === 4 && ajax.status === 200) {
-                            var info = ajax.responseText;
-                            if (FileUploaded_Handler) {
-                                FileUploaded_Handler(up, file, info);
+                        if (ajax.readyState === 4) {
+                            if (ajax.status === 200) {
+                                var info = ajax.responseText;
+                                if (FileUploaded_Handler) {
+                                    FileUploaded_Handler(up, file, info);
+                                }
+                            } else {
+                                uploader.trigger('Error', {
+                                    status: ajax.status,
+                                    response: ajax.responseText,
+                                    file: file,
+                                    code: -200
+                                });
                             }
                         }
                     };