diff --git a/core/model.py b/core/model.py
index c51ba2417da7d6d7530f29c2b0bc9f5090d810ea..b4150155db9677124eabab079f003743fc6c4d8b 100755
--- a/core/model.py
+++ b/core/model.py
@@ -47,7 +47,7 @@ class Model(object):
     def get_infer_results(self):
         return self._infer_results
 
-    def get_cost_op(self):
+    def get_avg_cost(self):
         """R
         """
         return self._cost
diff --git a/core/trainers/cluster_trainer.py b/core/trainers/cluster_trainer.py
index 327dffe0cdbbf8db22be1e5a9b59d4e770563b37..faa960359bc82d6130302002a99fb664c7374249 100755
--- a/core/trainers/cluster_trainer.py
+++ b/core/trainers/cluster_trainer.py
@@ -82,7 +82,7 @@ class ClusterTrainer(TranspileTrainer):
 
         strategy = self.build_strategy()
         optimizer = fleet.distributed_optimizer(optimizer, strategy)
-        optimizer.minimize(self.model.get_cost_op())
+        optimizer.minimize(self.model.get_avg_cost())
 
         if fleet.is_server():
             context['status'] = 'server_pass'
@@ -114,7 +114,7 @@ class ClusterTrainer(TranspileTrainer):
 
         program = fluid.compiler.CompiledProgram(
             fleet.main_program).with_data_parallel(
-            loss_name=self.model.get_cost_op().name,
+            loss_name=self.model.get_avg_cost().name,
             build_strategy=self.strategy.get_build_strategy(),
             exec_strategy=self.strategy.get_execute_strategy())
 
diff --git a/core/trainers/ctr_coding_trainer.py b/core/trainers/ctr_coding_trainer.py
index e6979a922618c4ea118da26c1a08e6808276e482..b6b987dde09949c88285cccf3fd6adad7108677d 100755
--- a/core/trainers/ctr_coding_trainer.py
+++ b/core/trainers/ctr_coding_trainer.py
@@ -88,7 +88,7 @@ class CtrPaddleTrainer(Trainer):
         optimizer = self.model.optimizer()
 
         optimizer = fleet.distributed_optimizer(optimizer, strategy={"use_cvm": False})
-        optimizer.minimize(self.model.get_cost_op())
+        optimizer.minimize(self.model.get_avg_cost())
 
         if fleet.is_server():
             context['status'] = 'server_pass'
diff --git a/core/trainers/ctr_modul_trainer.py b/core/trainers/ctr_modul_trainer.py
index d486767e300ce9d8ce6f56b4fb6b9820779e2df6..cb16b3c43ef48b6497d69cf222ef279a4a80b189 100755
--- a/core/trainers/ctr_modul_trainer.py
+++ b/core/trainers/ctr_modul_trainer.py
@@ -129,7 +129,7 @@ class CtrPaddleTrainer(Trainer):
             model = self._exector_context[executor['name']]['model']
             self._metrics.update(model.get_metrics())
             runnnable_scope.append(scope)
-            runnnable_cost_op.append(model.get_cost_op())
+            runnnable_cost_op.append(model.get_avg_cost())
             for var in model._data_var:
                 if var.name in data_var_name_dict:
                     continue
@@ -146,7 +146,7 @@ class CtrPaddleTrainer(Trainer):
             model = self._exector_context[executor['name']]['model']
             program = model._build_param['model']['train_program']
             if not executor['is_update_sparse']:
-                program._fleet_opt["program_configs"][str(id(model.get_cost_op().block.program))]["push_sparse"] = []
+                program._fleet_opt["program_configs"][str(id(model.get_avg_cost().block.program))]["push_sparse"] = []
             if 'train_thread_num' not in executor:
                 executor['train_thread_num'] = self.global_config['train_thread_num']
             with fluid.scope_guard(scope):
diff --git a/core/trainers/online_learning_trainer.py b/core/trainers/online_learning_trainer.py
index 4a64d4c278859071019d0932d96015210402e12e..1e6c183fe7bf184509a61797cd707837b4839e21 100755
--- a/core/trainers/online_learning_trainer.py
+++ b/core/trainers/online_learning_trainer.py
@@ -78,7 +78,7 @@ class ClusterTrainer(TranspileTrainer):
         optimizer = self.model.optimizer()
         strategy = self.build_strategy()
         optimizer = fleet.distributed_optimizer(optimizer, strategy)
-        optimizer.minimize(self.model.get_cost_op())
+        optimizer.minimize(self.model.get_avg_cost())
 
         if fleet.is_server():
             context['status'] = 'server_pass'
diff --git a/core/trainers/single_trainer.py b/core/trainers/single_trainer.py
index e2f02f4bd76ae7c2c6f6a3be5744f70828b8a8e7..7690a1e7bdaf228078c4c1cef2522438ce4503cf 100755
--- a/core/trainers/single_trainer.py
+++ b/core/trainers/single_trainer.py
@@ -47,7 +47,7 @@ class SingleTrainer(TranspileTrainer):
     def init(self, context):
         self.model.train_net()
         optimizer = self.model.optimizer()
-        optimizer.minimize((self.model.get_cost_op()))
+        optimizer.minimize((self.model.get_avg_cost()))
 
         self.fetch_vars = []
         self.fetch_alias = []
@@ -74,7 +74,7 @@ class SingleTrainer(TranspileTrainer):
 
         program = fluid.compiler.CompiledProgram(
             fluid.default_main_program()).with_data_parallel(
-            loss_name=self.model.get_cost_op().name)
+            loss_name=self.model.get_avg_cost().name)
 
         metrics_varnames = []
         metrics_format = []
diff --git a/doc/design.md b/doc/design.md
index 90a819fe5a42fa584930d628e33ed76e451e823f..2975d77f14e461547921f74b9ced5cf73703e2e7 100644
--- a/doc/design.md
+++ b/doc/design.md
@@ -153,7 +153,7 @@ class Model(object):
     def infer_net(self):
         pass
 
-    def get_cost_op(self):
+    def get_avg_cost(self):
     return self._cost
 
 ```
diff --git a/models/contentunderstanding/classification/model.py b/models/contentunderstanding/classification/model.py
index 18db63a5591340e2137d8a1af3e74d73f2fe0f52..f8bb3fea3492550e399f9b9894b99776052a0877 100644
--- a/models/contentunderstanding/classification/model.py
+++ b/models/contentunderstanding/classification/model.py
@@ -59,7 +59,7 @@ class Model(ModelBase):
         self.cost = avg_cost
         self._metrics["acc"] = acc
 
-    def get_cost_op(self):
+    def get_avg_cost(self):
         return self.cost
 
     def get_metrics(self):
diff --git a/models/contentunderstanding/tagspace/model.py b/models/contentunderstanding/tagspace/model.py
index eb01efbab1295829a939bfa8607bbe4c7418e37f..090d6c486feae2aa2f5cac1f38caaf99e02d099e 100644
--- a/models/contentunderstanding/tagspace/model.py
+++ b/models/contentunderstanding/tagspace/model.py
@@ -89,7 +89,7 @@ class Model(ModelBase):
         self.metrics["correct"] = correct
         self.metrics["cos_pos"] = cos_pos
 
-    def get_cost_op(self):
+    def get_avg_cost(self):
         return self.cost
 
     def get_metrics(self):