diff --git a/paddle/fluid/operators/mish_op.cc b/paddle/fluid/operators/mish_op.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ea754b5b1e9413fbd28b351c13fe1da549ccfafb
--- /dev/null
+++ b/paddle/fluid/operators/mish_op.cc
@@ -0,0 +1,121 @@
+/* Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include "paddle/fluid/operators/mish_op.h"
+#include <memory>
+#include <string>
+
+namespace paddle {
+namespace operators {
+
+class MishOp : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+  void InferShape(framework::InferShapeContext *ctx) const override {
+    OP_INOUT_CHECK(ctx->HasInput("X"), "Input", "X", "mish");
+    OP_INOUT_CHECK(ctx->HasOutput("Out"), "Output", "Out", "mish");
+
+    ctx->ShareDim("X", /*->*/ "Out");
+    ctx->ShareLoD("X", /*->*/ "Out");
+  }
+
+ protected:
+  framework::OpKernelType GetExpectedKernelType(
+      const framework::ExecutionContext &ctx) const override {
+    return framework::OpKernelType(
+        OperatorWithKernel::IndicateVarDataType(ctx, "X"),
+        ctx.device_context());
+  }
+};
+
+class MishOpMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  void Make() override {
+    AddInput("X", "Input of Mish operator");
+    AddOutput("Out", "Output of Mish operator");
+    AddAttr<float>(
+        "threshold",
+        "Constant threshold of softplus in Mish operator. Approximate value "
+        "of softplus will be used if absolute value of input is greater than "
+        ":attr:`threshold`")
+        .SetDefault(20.f);
+    AddComment(R"DOC(
+Mish Activation Operator.
+
+..  math::
+    softplus = \begin{cases}
+            x, \text{if } x > \text{threshold} \\
+            e^{x}, \text{if } x < -\text{threshold} \\
+            \ln(1 + e^{x}),  \text{otherwise}
+          \end{cases}
+
+    out = x * \tanh(softplus)
+
+)DOC");
+  }
+};
+
+// The operator to calculate gradients of a prelu operator.
+class MishGradOp : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+  void InferShape(framework::InferShapeContext *ctx) const override {
+    OP_INOUT_CHECK(ctx->HasInput("X"), "Input", "X", "mish");
+    OP_INOUT_CHECK(ctx->HasInput(framework::GradVarName("Out")), "Input",
+                   "Out@GRAD", "mish");
+
+    auto x_grad_name = framework::GradVarName("X");
+    if (ctx->HasOutput(x_grad_name)) {
+      ctx->SetOutputDim(x_grad_name, ctx->GetInputDim("X"));
+    }
+  }
+
+ protected:
+  framework::OpKernelType GetExpectedKernelType(
+      const framework::ExecutionContext &ctx) const override {
+    return framework::OpKernelType(
+        OperatorWithKernel::IndicateVarDataType(ctx, "X"),
+        ctx.device_context());
+  }
+};
+
+template <typename T>
+class MishGradOpMaker : public framework::SingleGradOpMaker<T> {
+ public:
+  using framework::SingleGradOpMaker<T>::SingleGradOpMaker;
+
+ protected:
+  void Apply(GradOpPtr<T> op) const override {
+    op->SetType("mish_grad");
+    op->SetInput("X", this->Input("X"));
+    op->SetInput(framework::GradVarName("Out"), this->OutputGrad("Out"));
+    op->SetOutput(framework::GradVarName("X"), this->InputGrad("X"));
+    op->SetAttrMap(this->Attrs());
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+
+REGISTER_OPERATOR(mish, ops::MishOp, ops::MishOpMaker,
+                  ops::MishGradOpMaker<paddle::framework::OpDesc>,
+                  ops::MishGradOpMaker<paddle::imperative::OpBase>);
+REGISTER_OPERATOR(mish_grad, ops::MishGradOp);
+REGISTER_OP_CPU_KERNEL(
+    mish, ops::MishFP32CPUKernel<paddle::platform::CPUDeviceContext>,
+    ops::MishCPUKernel<paddle::platform::CPUDeviceContext, double>);
+REGISTER_OP_CPU_KERNEL(
+    mish_grad, ops::MishGradFP32CPUKernel<paddle::platform::CPUDeviceContext>,
+    ops::MishGradCPUKernel<paddle::platform::CPUDeviceContext, double>);
diff --git a/paddle/fluid/operators/mish_op.cu b/paddle/fluid/operators/mish_op.cu
new file mode 100644
index 0000000000000000000000000000000000000000..77817e526e13d0618fbbfea313fe1d4c28cd582d
--- /dev/null
+++ b/paddle/fluid/operators/mish_op.cu
@@ -0,0 +1,173 @@
+/* Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include "paddle/fluid/framework/op_registry.h"
+#include "paddle/fluid/operators/mish_op.h"
+#include "paddle/fluid/platform/cuda_primitives.h"
+#include "paddle/fluid/platform/gpu_launch_config.h"
+
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+
+template <typename T>
+__global__ void KeMishFw(const T* in, T* out, const int numel,
+                         const float threshold) {
+  int tid = blockIdx.x * blockDim.x + threadIdx.x;
+  int stride = blockDim.x * gridDim.x;
+  for (; tid < numel; tid += stride) {
+    T x = in[tid];
+    T sp = CalcSoftplus<T>(x, threshold);
+    out[tid] = x * tanh(sp);
+  }
+}
+
+// expf instead of exp should be used for float type, complement
+// and register float kernel separatelly
+__global__ void KeMishFwFP32(const float* in, float* out, const int numel,
+                             const float threshold) {
+  int tid = blockIdx.x * blockDim.x + threadIdx.x;
+  int stride = blockDim.x * gridDim.x;
+  for (; tid < numel; tid += stride) {
+    float x = in[tid];
+    float sp = CalcSoftplusFP32(x, threshold);
+    out[tid] = x * tanhf(sp);
+  }
+}
+
+template <typename T>
+__global__ void KeMishBw(const T* in, const T* dout, T* din, const int numel,
+                         const float threshold) {
+  int tid = blockIdx.x * blockDim.x + threadIdx.x;
+  int stride = blockDim.x * gridDim.x;
+  for (; tid < numel; tid += stride) {
+    T x = in[tid];
+    T sp = CalcSoftplus<T>(x, threshold);
+    T tsp = tanh(sp);
+    T grad_sp = -expm1(-sp);
+    T grad_tsp = (static_cast<T>(1) - tsp * tsp) * grad_sp;
+    din[tid] = dout[tid] * (x * grad_tsp + tsp);
+  }
+}
+
+__global__ void KeMishBwFP32(const float* in, const float* dout, float* din,
+                             const int numel, const float threshold) {
+  int tid = blockIdx.x * blockDim.x + threadIdx.x;
+  int stride = blockDim.x * gridDim.x;
+  for (; tid < numel; tid += stride) {
+    float x = in[tid];
+    float sp = CalcSoftplusFP32(x, threshold);
+    float tsp = tanhf(sp);
+    float grad_sp = -expm1f(-sp);
+    float grad_tsp = (static_cast<float>(1) - tsp * tsp) * grad_sp;
+    din[tid] = dout[tid] * (x * grad_tsp + tsp);
+  }
+}
+
+template <typename DeviceContext, typename T>
+class MishCUDAKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* out = ctx.Output<Tensor>("Out");
+
+    const float threshold = ctx.Attr<float>("threshold");
+
+    const T* x_data = x->data<T>();
+    T* out_data = out->mutable_data<T>(ctx.GetPlace());
+
+    const int numel = x->numel();
+
+    platform::GpuLaunchConfig config = platform::getGpuLaunchConfig(numel, ctx);
+    KeMishFw<T><<<config.blocks, config.threads, 0,
+                  ctx.cuda_device_context().stream()>>>(x_data, out_data, numel,
+                                                        threshold);
+  }
+};
+
+template <typename DeviceContext>
+class MishFP32CUDAKernel : public framework::OpKernel<float> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* out = ctx.Output<Tensor>("Out");
+
+    const float threshold = ctx.Attr<float>("threshold");
+
+    const float* x_data = x->data<float>();
+    float* out_data = out->mutable_data<float>(ctx.GetPlace());
+
+    const int numel = x->numel();
+
+    platform::GpuLaunchConfig config = platform::getGpuLaunchConfig(numel, ctx);
+    KeMishFwFP32<<<config.blocks, config.threads, 0,
+                   ctx.cuda_device_context().stream()>>>(x_data, out_data,
+                                                         numel, threshold);
+  }
+};
+
+template <typename DeviceContext, typename T>
+class MishGradCUDAKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* dout = ctx.Input<Tensor>(framework::GradVarName("Out"));
+    auto* dx = ctx.Output<Tensor>(framework::GradVarName("X"));
+
+    auto threshold = ctx.Attr<float>("threshold");
+
+    const T* x_data = x->data<T>();
+    const T* dout_data = dout->data<T>();
+    T* dx_data = dx->mutable_data<T>(ctx.GetPlace());
+
+    const int numel = x->numel();
+
+    platform::GpuLaunchConfig config = platform::getGpuLaunchConfig(numel, ctx);
+    KeMishBw<T><<<config.blocks, config.threads, 0,
+                  ctx.cuda_device_context().stream()>>>(
+        x_data, dout_data, dx_data, numel, threshold);
+  }
+};
+
+template <typename DeviceContext>
+class MishGradFP32CUDAKernel : public framework::OpKernel<float> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* dout = ctx.Input<Tensor>(framework::GradVarName("Out"));
+    auto* dx = ctx.Output<Tensor>(framework::GradVarName("X"));
+
+    auto threshold = ctx.Attr<float>("threshold");
+
+    const float* x_data = x->data<float>();
+    const float* dout_data = dout->data<float>();
+    float* dx_data = dx->mutable_data<float>(ctx.GetPlace());
+
+    const int numel = x->numel();
+
+    platform::GpuLaunchConfig config = platform::getGpuLaunchConfig(numel, ctx);
+    KeMishBwFP32<<<config.blocks, config.threads, 0,
+                   ctx.cuda_device_context().stream()>>>(
+        x_data, dout_data, dx_data, numel, threshold);
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+REGISTER_OP_CUDA_KERNEL(
+    mish, ops::MishFP32CUDAKernel<paddle::platform::CUDADeviceContext>,
+    ops::MishCUDAKernel<paddle::platform::CUDADeviceContext, double>)
+REGISTER_OP_CUDA_KERNEL(
+    mish_grad, ops::MishGradFP32CUDAKernel<paddle::platform::CUDADeviceContext>,
+    ops::MishGradCUDAKernel<paddle::platform::CUDADeviceContext, double>)
diff --git a/paddle/fluid/operators/mish_op.h b/paddle/fluid/operators/mish_op.h
new file mode 100644
index 0000000000000000000000000000000000000000..86ccb57d929e5dec72fe67185530478109e2d7f0
--- /dev/null
+++ b/paddle/fluid/operators/mish_op.h
@@ -0,0 +1,137 @@
+/* Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#pragma once
+#include "paddle/fluid/framework/op_registry.h"
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+
+template <typename T>
+HOSTDEVICE static T CalcSoftplus(T x, float threshold) {
+  if (threshold > 0 && x > threshold) {
+    return x;
+  } else if (threshold > 0 && x < -threshold) {
+    return exp(x);
+  } else {
+    return log1p(exp(x));
+  }
+}
+
+// expf instead of exp should be used for float type, complement
+// and register float kernel separatelly
+HOSTDEVICE static float CalcSoftplusFP32(float x, float threshold) {
+  if (threshold > 0 && x > threshold) {
+    return x;
+  } else if (threshold > 0 && x < -threshold) {
+    return expf(x);
+  } else {
+    return log1pf(expf(x));
+  }
+}
+
+template <typename DeviceContext, typename T>
+class MishCPUKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* out = ctx.Output<Tensor>("Out");
+
+    const float threshold = ctx.Attr<float>("threshold");
+
+    const T* x_data = x->data<T>();
+    T* out_data = out->mutable_data<T>(ctx.GetPlace());
+
+    int numel = x->numel();
+    for (int i = 0; i < numel; i++) {
+      T x_d = x_data[i];
+      T sp = CalcSoftplus<T>(x_d, threshold);
+      out_data[i] = x_d * std::tanh(sp);
+    }
+  }
+};
+
+template <typename DeviceContext>
+class MishFP32CPUKernel : public framework::OpKernel<float> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* out = ctx.Output<Tensor>("Out");
+
+    const float threshold = ctx.Attr<float>("threshold");
+
+    const float* x_data = x->data<float>();
+    float* out_data = out->mutable_data<float>(ctx.GetPlace());
+
+    int numel = x->numel();
+    for (int i = 0; i < numel; i++) {
+      float x_d = x_data[i];
+      float sp = CalcSoftplusFP32(x_d, threshold);
+      out_data[i] = x_d * std::tanh(sp);
+    }
+  }
+};
+
+template <typename DeviceContext, typename T>
+class MishGradCPUKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* dx = ctx.Output<Tensor>(framework::GradVarName("X"));
+    auto* dout = ctx.Input<Tensor>(framework::GradVarName("Out"));
+
+    auto threshold = ctx.Attr<float>("threshold");
+
+    const T* x_data = x->data<T>();
+    const T* dout_data = dout->data<T>();
+    T* dx_data = dx->mutable_data<T>(ctx.GetPlace());
+
+    int numel = x->numel();
+    for (int i = 0; i < numel; i++) {
+      T x_d = x_data[i];
+      T sp = CalcSoftplus<T>(x_d, threshold);
+      T tsp = std::tanh(sp);
+      T grad_sp = -std::expm1(-sp);
+      T grad_tsp = (static_cast<T>(1) - tsp * tsp) * grad_sp;
+      dx_data[i] = dout_data[i] * (x_d * grad_tsp + tsp);
+    }
+  }
+};
+
+template <typename DeviceContext>
+class MishGradFP32CPUKernel : public framework::OpKernel<float> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* x = ctx.Input<Tensor>("X");
+    auto* dx = ctx.Output<Tensor>(framework::GradVarName("X"));
+    auto* dout = ctx.Input<Tensor>(framework::GradVarName("Out"));
+
+    auto threshold = ctx.Attr<float>("threshold");
+
+    const float* x_data = x->data<float>();
+    const float* dout_data = dout->data<float>();
+    float* dx_data = dx->mutable_data<float>(ctx.GetPlace());
+
+    int numel = x->numel();
+    for (int i = 0; i < numel; i++) {
+      float x_d = x_data[i];
+      float sp = CalcSoftplusFP32(x_d, threshold);
+      float tsp = std::tanh(sp);
+      float grad_sp = -std::expm1f(-sp);
+      float grad_tsp = (static_cast<float>(1) - tsp * tsp) * grad_sp;
+      dx_data[i] = dout_data[i] * (x_d * grad_tsp + tsp);
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
diff --git a/python/paddle/fluid/layers/nn.py b/python/paddle/fluid/layers/nn.py
index d76d4e6bc0915a9c42ab6ea20e94c9a7c714577e..3ca172691a62b9978d06eb9a8391cfd4694c480f 100644
--- a/python/paddle/fluid/layers/nn.py
+++ b/python/paddle/fluid/layers/nn.py
@@ -202,6 +202,7 @@ __all__ = [
     'filter_by_instag',
     'shard_index',
     'hard_swish',
+    'mish',
     'gather_tree',
     'uniform_random',
     'randint',
@@ -16353,6 +16354,81 @@ def elementwise_equal(x, y, name=None):
     return out
 
 
+@templatedoc()
+def mish(x, threshold=20, name=None):
+    """
+    This operator implements the mish activation function.
+    Refer to `Mish: A Self Regularized Non-Monotonic Neural
+    Activation Function <https://arxiv.org/abs/1908.08681>`_
+
+
+    The formula is as follows if :attr:`threshold` is :code:`None` or negative:
+
+    .. math::
+
+        out = x * \\tanh(\\ln(1 + e^{x}))
+
+    The formula is as follows if :attr:`threshold` is set as positive value:
+
+    .. math::
+
+	out = \\begin{cases}
+		x \\ast \\tanh(x), \\text{if } x > \\text{threshold} \\\\
+		x \\ast \\tanh(e^{x}), \\text{if } x < -\\text{threshold} \\\\
+		x \\ast \\tanh(\\ln(1 + e^{x})),  \\text{otherwise}
+	      \\end{cases}
+
+    Args:
+        x (Variable): Input feature, multi-dimensional Tensor. The data type
+                      should be float16, float32 or float64.
+        threshold (float|None): threshold for softplus in Mish operator.
+                Approximate value of softplus will be used if absolute value
+                of input is greater than :attr:threshold and :attr:threshold
+                is set as positive value. For none or negative threshold,
+                approximate value is not used. Default 20.
+        name (str, optional): The default value is None. Normally there is no
+                need for user to set this property. For more information, please
+                refer to :ref:`api_guide_Name`
+
+    Returns:
+        Variable: The output tensor with the same shape and data type as input.
+
+
+    Examples:
+
+    .. code-block:: python
+
+        import paddle.fluid as fluid
+        import numpy as np
+
+        DATATYPE='float32'
+
+        x_data = np.array([i for i in range(1,5)]).reshape([1,1,4]).astype(DATATYPE)
+
+        x = fluid.data(name="x", shape=[None,1,4], dtype=DATATYPE)
+        y = fluid.layers.mish(x)
+
+        place = fluid.CPUPlace()
+        # place = fluid.CUDAPlace(0)
+        exe = fluid.Executor(place)
+        out, = exe.run(feed={'x':x_data}, fetch_list=[y.name])
+        print(out)  # [[0.66666667, 1.66666667, 3., 4.]]
+    """
+    check_variable_and_dtype(x, 'x', ['float32', 'float64'], 'mish')
+    check_type(threshold, 'threshold', (float, int), 'mish')
+    assert threshold > 0, "threshold of mish should be greater than 0, " \
+                          "but got {}".format(threshold)
+
+    helper = LayerHelper('mish', **locals())
+    out = helper.create_variable_for_type_inference(dtype=x.dtype)
+    helper.append_op(
+        type='mish',
+        inputs={'X': x},
+        outputs={'Out': out},
+        attrs={'threshold': threshold or -1})
+    return out
+
+
 def flip(input, dims, name=None):
     """
 
diff --git a/python/paddle/fluid/tests/unittests/test_layers.py b/python/paddle/fluid/tests/unittests/test_layers.py
index d69b0831d6855237fad97068055d520ca57ffacf..a89d7a49794e9b09ab61265df9aac9b668f6a702 100644
--- a/python/paddle/fluid/tests/unittests/test_layers.py
+++ b/python/paddle/fluid/tests/unittests/test_layers.py
@@ -2653,6 +2653,13 @@ class TestBook(LayerTest):
             out = layers.softsign(input, name='softsign')
             return (out)
 
+    def make_mish(self):
+        with program_guard(fluid.default_main_program(),
+                           fluid.default_startup_program()):
+            input = self._get_data(name="input", shape=[16], dtype="float32")
+            out = layers.mish(input, name='mish')
+            return (out)
+
     def make_cross_entropy(self):
         with program_guard(fluid.default_main_program(),
                            fluid.default_startup_program()):
diff --git a/python/paddle/fluid/tests/unittests/test_mish_op.py b/python/paddle/fluid/tests/unittests/test_mish_op.py
new file mode 100644
index 0000000000000000000000000000000000000000..8cc785e450f0bac54f2193aac45165bc9b800b73
--- /dev/null
+++ b/python/paddle/fluid/tests/unittests/test_mish_op.py
@@ -0,0 +1,102 @@
+#   Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import unittest
+import numpy as np
+import six
+import paddle.fluid as fluid
+import paddle.fluid.core as core
+from paddle.fluid import Program, program_guard
+from op_test import OpTest, skip_check_grad_ci
+
+
+class TestMishOpError(unittest.TestCase):
+    def test_errors(self):
+        with program_guard(Program()):
+            # The input type must be Variable.
+            self.assertRaises(TypeError, fluid.layers.mish, 0.1, 20)
+            # The input dtype must be float16, float32, float64.
+            x_int32 = fluid.data(name='x_int32', shape=[12, 10], dtype='int32')
+            self.assertRaises(TypeError, fluid.layers.mish, x_int32, 20)
+            # support the input dtype is float32
+            x_fp16 = fluid.layers.data(
+                name='x_fp16', shape=[12, 10], dtype='float32')
+            fluid.layers.mish(x_fp16, threshold=20)
+
+
+class MishTest(OpTest):
+    def setUp(self):
+        self.init_dtype()
+        self.init_input_shape()
+        self.init_input_range()
+        self.init_threshold()
+        self.op_type = "mish"
+
+        x_np = np.random.uniform(self.x_range[0], self.x_range[1],
+                                 self.x_shape).astype(self.dtype)
+        self.inputs = {'X': x_np}
+
+        softplus = x_np * (x_np > self.threshold) + np.exp(x_np) * \
+                    (x_np < -self.threshold) + np.log(np.exp(x_np) + 1.) * \
+                    (x_np >= -self.threshold) * (x_np <= self.threshold)
+        out_np = x_np * np.tanh(softplus)
+
+        self.outputs = {'Out': out_np}
+        self.attrs = {'threshold': self.threshold}
+
+    def init_dtype(self):
+        self.dtype = 'float32'
+
+    def init_input_shape(self):
+        self.x_shape = (10, 12)
+
+    def init_input_range(self):
+        self.x_range = [-1, 1]
+
+    def init_threshold(self):
+        self.threshold = 5.
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_check_grad(self):
+        self.check_grad(['X'], 'Out')
+
+
+class MishTestUpperThresh(MishTest):
+    def init_input_range(self):
+        self.x_range = [6, 7]
+
+
+class MishTestLowerThresh(MishTest):
+    def init_input_range(self):
+        self.x_range = [-7, -6]
+
+
+# mish op contain calculation like: tanh, exp, log, while tanh
+# may have diff on CPUPlace(see test_activation_op.py::TestTanh),
+# especially when abs(x) is a large value, only check input value
+# in range [-1, 1] for float64 here.
+class MishTestFP64(MishTest):
+    def init_dtype(self):
+        self.dtype = 'float64'
+
+    def init_input_range(self):
+        self.x_range = [-1, 1]
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/python/paddle/fluid/tests/unittests/white_list/op_accuracy_white_list.py b/python/paddle/fluid/tests/unittests/white_list/op_accuracy_white_list.py
index ae99aeff557e4aa31f2868fbb8be9d038d5538ca..db5ad92ff5ead4fbc609209692268bef254d8c27 100644
--- a/python/paddle/fluid/tests/unittests/white_list/op_accuracy_white_list.py
+++ b/python/paddle/fluid/tests/unittests/white_list/op_accuracy_white_list.py
@@ -70,6 +70,7 @@ NO_FP64_CHECK_GRAD_OP_LIST = [
     'squared_l2_distance', \
     'squared_l2_norm', \
     'tanh', \
+    'mish', \
     'transpose2', \
     'trilinear_interp', \
     'var_conv_2d', \