diff --git a/python/paddle/trainer_config_helpers/layers.py b/python/paddle/trainer_config_helpers/layers.py
index b5e10ef81009a00e76b0c4147b404ba0aaba72b3..7cd290023aba10eba63d307b96aac57734d043c0 100644
--- a/python/paddle/trainer_config_helpers/layers.py
+++ b/python/paddle/trainer_config_helpers/layers.py
@@ -494,8 +494,7 @@ def scaling_projection(input, param_attr=None):
     :return: A ScalingProjection object
     :rtype: ScalingProjection
     """
-    proj = ScalingProjection(input_layer_name=input.name,
-                             **param_attr.attr)
+    proj = ScalingProjection(input_layer_name=input.name, **param_attr.attr)
     proj.origin = input
     return proj
 
@@ -2783,7 +2782,12 @@ class SubsequenceInput(object):
 
 
 @wrap_name_default("recurrent_group")
-def recurrent_group(step, input, reverse=False, name=None, targetInlink=None):
+def recurrent_group(step,
+                    input,
+                    reverse=False,
+                    name=None,
+                    targetInlink=None,
+                    is_generating=False):
     """
     Recurrent layer group is an extremely flexible recurrent unit in
     PaddlePaddle. As long as the user defines the calculation done within a
@@ -2848,6 +2852,12 @@ def recurrent_group(step, input, reverse=False, name=None, targetInlink=None):
 
     :type targetInlink: LayerOutput|SubsequenceInput
 
+    :param is_generating: If is generating, none of input type should be LayerOutput;
+                          else, for training or testing, one of the input type must 
+                          be LayerOutput.
+
+    : type is_generating: bool
+    
     :return: LayerOutput object.
     :rtype: LayerOutput
     """
@@ -2895,6 +2905,7 @@ def recurrent_group(step, input, reverse=False, name=None, targetInlink=None):
         seq_reversed=reverse,
         target_inlinkname=targetInlinkName)
     in_args = []
+    has_LayerOutput = True
     for each_input in input:
         assert is_single_input(each_input)
         if isinstance(each_input, LayerOutput):
@@ -2902,6 +2913,7 @@ def recurrent_group(step, input, reverse=False, name=None, targetInlink=None):
         elif isinstance(each_input, SubsequenceInput):
             in_args.append(each_input.input)
         else:
+            has_LayerOutput = False
             mem_name = "__%s_memory__" % each_input.input.name
             mem = memory(
                 name=mem_name,
@@ -2915,6 +2927,8 @@ def recurrent_group(step, input, reverse=False, name=None, targetInlink=None):
                 mix += identity_projection(mem)
             in_args.append(mem)
 
+    assert (is_generating != has_LayerOutput)
+
     layer_outs = step(*in_args)
 
     if isinstance(layer_outs, LayerOutput):
@@ -3206,7 +3220,11 @@ def beam_search(step,
         return predict
 
     tmp = recurrent_group(
-        step=__real_step__, input=real_input, reverse=False, name=name)
+        step=__real_step__,
+        input=real_input,
+        reverse=False,
+        name=name,
+        is_generating=True)
 
     return tmp