diff --git a/python/paddle/trainer_config_helpers/layers.py b/python/paddle/trainer_config_helpers/layers.py
index 617fbff948bf03098eca4a31f44d4ff05e73dbcf..ca0b5dbfbffd138ffaf6f3a17daf217fed69213c 100644
--- a/python/paddle/trainer_config_helpers/layers.py
+++ b/python/paddle/trainer_config_helpers/layers.py
@@ -3592,10 +3592,9 @@ def lstm_step_layer(input,
     :type gate_act: BaseActivation
     :param state_act: State Activation Type. TanhActivation is the default.
     :type state_act: BaseActivation
-    :param bias_attr: The bias attribute. If the parameter is set to False or an object
-                      whose type is not ParameterAttribute, no bias is defined. If the
-                      parameter is set to True, the bias is initialized to zero.
-    :type bias_attr: ParameterAttribute | None | bool | Any
+    :param bias_attr: The bias attribute. If the parameter is set to
+                     True or None, the bias is initialized to zero.
+    :type bias_attr: ParameterAttribute | None | True
     :param layer_attr: layer's extra attribute.
     :type layer_attr: ExtraLayerAttribute
     :return: LayerOutput object.
diff --git a/python/paddle/trainer_config_helpers/networks.py b/python/paddle/trainer_config_helpers/networks.py
index 3821d075cba5d39b5808a39093b8570d9302b667..a5e7aca24a23bf7011e03929578b7fa6807e8840 100644
--- a/python/paddle/trainer_config_helpers/networks.py
+++ b/python/paddle/trainer_config_helpers/networks.py
@@ -698,14 +698,16 @@ def lstmemory_unit(input,
     :param state_act: state activiation type of lstm.
     :type state_act: BaseActivation
     :param input_proj_bias_attr: bias attribute for input to hidden projection.
-                False means no bias, None means default bias.
-    :type input_proj_bias_attr: ParameterAttribute|False|None
+                False or None means no bias. If the parameter is set to True,
+                the bias is initialized to zero.
+    :type input_proj_bias_attr: ParameterAttribute|bool|None
     :param input_proj_layer_attr: extra layer attribute for input to hidden
                 projection of the LSTM unit, such as dropout, error clipping.
     :type input_proj_layer_attr: ExtraLayerAttribute
     :param lstm_bias_attr: bias parameter attribute of lstm layer.
-                False means no bias, None means default bias.
-    :type lstm_bias_attr: ParameterAttribute|False|None
+                If the parameter is set to True or None,
+                the bias is initialized to zero.
+    :type lstm_bias_attr: ParameterAttribute|True|None
     :param lstm_layer_attr: extra attribute of lstm layer.
     :type lstm_layer_attr: ExtraLayerAttribute
     :return: lstmemory unit name.
@@ -805,11 +807,13 @@ def lstmemory_group(input,
     :param state_act: state activiation type of lstm.
     :type state_act: BaseActivation
     :param lstm_bias_attr: bias parameter attribute of lstm layer.
-                           False means no bias, None means default bias.
-    :type lstm_bias_attr: ParameterAttribute|False|None
+                If the parameter is set to True or None, the bias is
+                initialized to zero.
+    :type lstm_bias_attr: ParameterAttribute|True|None
     :param input_proj_bias_attr: bias attribute for input to hidden projection.
-                False means no bias, None means default bias.
-    :type input_proj_bias_attr: ParameterAttribute|False|None
+                False or None means no bias. If the parameter is set to True,
+                the bias is initialized to zero.
+    :type input_proj_bias_attr: ParameterAttribute|bool|None
     :param input_proj_layer_attr: extra layer attribute for input to hidden
                 projection of the LSTM unit, such as dropout, error clipping.
     :type input_proj_layer_attr: ExtraLayerAttribute