diff --git a/python/paddle/fluid/dygraph/nn.py b/python/paddle/fluid/dygraph/nn.py
index e9139156a14919af1ab26872f27f75cc9d985989..b06fddf59fbe6a6e623110573d2f804a70702a66 100644
--- a/python/paddle/fluid/dygraph/nn.py
+++ b/python/paddle/fluid/dygraph/nn.py
@@ -958,7 +958,7 @@ class Linear(layers.Layer):
         tmp = self._helper.create_variable_for_type_inference(self._dtype)
         self._helper.append_op(
             type="matmul", inputs=inputs, outputs={"Out": tmp}, attrs=attrs)
-        if self.bias:
+        if self.bias is not None:
             pre_activation = self._helper.create_variable_for_type_inference(
                 dtype=self._dtype)
             self._helper.append_op(
diff --git a/python/paddle/fluid/layers/loss.py b/python/paddle/fluid/layers/loss.py
index 18790317e53ac10d4fe7b20849fc70995574a608..04a803dfa546168078be6dc1a20ede58836e3deb 100644
--- a/python/paddle/fluid/layers/loss.py
+++ b/python/paddle/fluid/layers/loss.py
@@ -479,7 +479,7 @@ def edit_distance(input,
         label = erased_label
 
     this_inputs = {"Hyps": [input], "Refs": [label]}
-    if input_length and label_length:
+    if input_length is not None and label_length is not None:
         this_inputs['HypsLength'] = [input_length]
         this_inputs['RefsLength'] = [label_length]
 
diff --git a/python/paddle/fluid/layers/nn.py b/python/paddle/fluid/layers/nn.py
index de3a9ed39c021862d623525b6d520d7cd356b7f5..7eaa9c0dcea801724c71b28a2f50be19c8e82226 100644
--- a/python/paddle/fluid/layers/nn.py
+++ b/python/paddle/fluid/layers/nn.py
@@ -1137,7 +1137,7 @@ def chunk_eval(input,
 
     this_input = {"Inference": [input], "Label": [label]}
 
-    if seq_length:
+    if seq_length is not None:
         this_input["SeqLength"] = [seq_length]
 
     helper.append_op(