diff --git a/python/paddle/v2/trainer.py b/python/paddle/v2/trainer.py
index 58ec6dd5fe5002b203d53cefb27b32d3af37d3fd..21a1642c36a2cc428f2334c101a2b3fb22608bd6 100644
--- a/python/paddle/v2/trainer.py
+++ b/python/paddle/v2/trainer.py
@@ -122,7 +122,6 @@ class SGD(ITrainer):
                 self.__gradient_machine__.eval(batch_evaluator)
                 for each_param in self.__gradient_machine__.getParameters():
                     updater.update(each_param)
-                # Get cost. We use numpy to calculate total cost for this batch.
                 cost_sum = out_args.sumCosts()
                 cost = cost_sum / len(data_batch)
                 updater.finishBatch(cost)