diff --git a/paddle/fluid/operators/sigmoid_cross_entropy_with_logits_op.cc b/paddle/fluid/operators/sigmoid_cross_entropy_with_logits_op.cc
index 368988d60da1a6753c05858e1222c4e9358db09b..14746fa95159d707be7c10c69a4ffc2211e17a93 100644
--- a/paddle/fluid/operators/sigmoid_cross_entropy_with_logits_op.cc
+++ b/paddle/fluid/operators/sigmoid_cross_entropy_with_logits_op.cc
@@ -18,6 +18,7 @@ namespace paddle {
 namespace operators {
 
 using framework::Tensor;
+const int kIgnoreIndex = -100;
 
 class SigmoidCrossEntropyWithLogitsOp : public framework::OperatorWithKernel {
  public:
@@ -100,11 +101,11 @@ class SigmoidCrossEntropyWithLogitsOpMaker
     AddOutput("Out",
               "(Tensor, default Tensor<float>), a 2-D tensor with shape N x D "
               " of elementwise logistic losses.");
-    AddAttr<int>(
-        "ignore_index",
-        "(int, default -100), Specifies a target value that is ignored and"
-        "does not contribute to the input gradient.")
-        .SetDefault(-100);
+    AddAttr<int>("ignore_index",
+                 "(int, default kIgnoreIndex), Specifies a target value that "
+                 "is ignored and"
+                 "does not contribute to the input gradient.")
+        .SetDefault(kIgnoreIndex);
     AddComment(R"DOC(
 SigmoidCrossEntropyWithLogits Operator.
 
diff --git a/python/paddle/fluid/layers/nn.py b/python/paddle/fluid/layers/nn.py
index 38da9173cce594635a53cf2cedafe6a4c1cf810e..f746e4424dec686213414a1a6683bf8999be3581 100644
--- a/python/paddle/fluid/layers/nn.py
+++ b/python/paddle/fluid/layers/nn.py
@@ -170,6 +170,8 @@ __all__ = [
     'bilinear_tensor_product',
 ]
 
+kIgnoreIndex = -100
+
 
 def fc(input,
        size,
@@ -1103,7 +1105,7 @@ def dropout(x,
     return out
 
 
-def cross_entropy(input, label, soft_label=False, ignore_index=-100):
+def cross_entropy(input, label, soft_label=False, ignore_index=kIgnoreIndex):
     """
     **Cross Entropy Layer**
 
@@ -4796,7 +4798,7 @@ def multiplex(inputs, index):
 def softmax_with_cross_entropy(logits,
                                label,
                                soft_label=False,
-                               ignore_index=-100,
+                               ignore_index=kIgnoreIndex,
                                numeric_stable_mode=False,
                                return_softmax=False):
     """
@@ -7892,7 +7894,10 @@ def mul(x, y, x_num_col_dims=1, y_num_col_dims=1, name=None):
 
 
 @templatedoc()
-def sigmoid_cross_entropy_with_logits(x, label, ignore_index=-100, name=None):
+def sigmoid_cross_entropy_with_logits(x,
+                                      label,
+                                      ignore_index=kIgnoreIndex,
+                                      name=None):
     """
     ${comment}