diff --git a/python/paddle/fluid/backward.py b/python/paddle/fluid/backward.py
index 812f68bdd849544456b2e0ebf0b739f4f92b09ea..3fb7019a450da5903952c59ee483d88fde42701a 100644
--- a/python/paddle/fluid/backward.py
+++ b/python/paddle/fluid/backward.py
@@ -572,8 +572,6 @@ def append_backward(loss, parameter_list=None, no_grad_set=None,
 
     program.current_block_idx = current_block_idx
     program._sync_with_cpp()
-    # FIXME(zcd): prevent loss.grad optimized by mem_opt.
-    loss.block.var(_append_grad_suffix_(loss.name)).persistable = True
 
     if parameter_list is not None:
         parameters = parameter_list