diff --git a/python/examples/fit_a_line/README.md b/python/examples/fit_a_line/README.md
index 8ea146e9b7a8e781cbebd004bd54c6e0adfba7c2..acc51938e39fc7b758071292e06b195ecfa558cb 100644
--- a/python/examples/fit_a_line/README.md
+++ b/python/examples/fit_a_line/README.md
@@ -46,5 +46,5 @@ python -m paddle_serving_server.serve --model uci_housing_model --thread 10 --po
 ### Client prediction
 
 ``` shell
-curl -H "Content-Type:application/json" -X POST -d '{"x": [0.0137, -0.1136, 0.2553, -0.0692, 0.0582, -0.0727, -0.1583, -0.0584, 0.6283, 0.4919, 0.1856, 0.0795, -0.0332], "fetch":["price"]}' http://127.0.0.1:9393/uci/prediction
+curl -H "Content-Type:application/json" -X POST -d '{"feed":[{"x": [0.0137, -0.1136, 0.2553, -0.0692, 0.0582, -0.0727, -0.1583, -0.0584, 0.6283, 0.4919, 0.1856, 0.0795, -0.0332]}], "fetch":["price"]}' http://127.0.0.1:9393/uci/prediction
 ```
diff --git a/python/paddle_serving_server/web_service.py b/python/paddle_serving_server/web_service.py
index 4a033cbcf1d32a55eaacbe9c0f6704e304e127b3..56cbd976e49bdd0743b4354a9c6a31872657f168 100755
--- a/python/paddle_serving_server/web_service.py
+++ b/python/paddle_serving_server/web_service.py
@@ -61,14 +61,15 @@ class WebService(object):
         if "fetch" not in request.json:
             abort(400)
         try:
-            feed, fetch = self.preprocess(request.json, request.json["fetch"])
+            feed, fetch = self.preprocess(request.json["feed"],
+                                          request.json["fetch"])
             if isinstance(feed, dict) and "fetch" in feed:
                 del feed["fetch"]
             fetch_map = self.client_service.predict(feed=feed, fetch=fetch)
             for key in fetch_map:
-                fetch_map[key] = fetch_map[key][0].tolist()
+                fetch_map[key] = fetch_map[key].tolist()
             result = self.postprocess(
-                feed=request.json, fetch=fetch, fetch_map=fetch_map)
+                feed=feed, fetch=fetch, fetch_map=fetch_map)
             result = {"result": result}
         except ValueError:
             result = {"result": "Request Value Error"}
@@ -83,8 +84,8 @@ class WebService(object):
         p_rpc = Process(target=self._launch_rpc_service)
         p_rpc.start()
 
-    def preprocess(self, feed={}, fetch=[]):
+    def preprocess(self, feed=[], fetch=[]):
         return feed, fetch
 
-    def postprocess(self, feed={}, fetch=[], fetch_map=None):
+    def postprocess(self, feed=[], fetch=[], fetch_map=None):
         return fetch_map
diff --git a/python/paddle_serving_server_gpu/web_service.py b/python/paddle_serving_server_gpu/web_service.py
index cb833ba32b20edeb22efd5b772506d32e05e4497..6482f9b252ca5520bdde31d6aa8e1069364e82a0 100644
--- a/python/paddle_serving_server_gpu/web_service.py
+++ b/python/paddle_serving_server_gpu/web_service.py
@@ -105,14 +105,15 @@ class WebService(object):
         if "fetch" not in request.json:
             abort(400)
         try:
-            feed, fetch = self.preprocess(request.json, request.json["fetch"])
+            feed, fetch = self.preprocess(request.json["feed"],
+                                          request.json["fetch"])
             if isinstance(feed, dict) and "fetch" in feed:
                 del feed["fetch"]
             fetch_map = self.client.predict(feed=feed, fetch=fetch)
             for key in fetch_map:
-                fetch_map[key] = fetch_map[key][0].tolist()
+                fetch_map[key] = fetch_map[key].tolist()
             result = self.postprocess(
-                feed=request.json, fetch=fetch, fetch_map=fetch_map)
+                feed=feed, fetch=fetch, fetch_map=fetch_map)
             result = {"result": result}
         except ValueError:
             result = {"result": "Request Value Error"}
@@ -131,8 +132,8 @@ class WebService(object):
         for p in server_pros:
             p.start()
 
-    def preprocess(self, feed={}, fetch=[]):
+    def preprocess(self, feed=[], fetch=[]):
         return feed, fetch
 
-    def postprocess(self, feed={}, fetch=[], fetch_map=None):
+    def postprocess(self, feed=[], fetch=[], fetch_map=None):
         return fetch_map