diff --git a/paddle/framework/CMakeLists.txt b/paddle/framework/CMakeLists.txt
index 4409c6feae218..e6e3b79d7bd11 100644
--- a/paddle/framework/CMakeLists.txt
+++ b/paddle/framework/CMakeLists.txt
@@ -16,3 +16,6 @@ py_proto_compile(framework_py_proto SRCS attr_type.proto op_proto.proto op_desc.
 # Generate an empty __init__.py to make framework_py_proto as a valid python module.
 add_custom_target(framework_py_proto_init ALL COMMAND ${CMAKE_COMMAND} -E touch __init__.py)
 add_dependencies(framework_py_proto framework_py_proto_init)
+
+proto_library(net_proto SRCS net_proto.proto DEPS op_proto)
+cc_library(net SRCS net.cc DEPS net_proto attr_type op_proto)
diff --git a/paddle/framework/net.cc b/paddle/framework/net.cc
new file mode 100644
index 0000000000000..73b3051235ee9
--- /dev/null
+++ b/paddle/framework/net.cc
@@ -0,0 +1,20 @@
+#include "paddle/framework/net.h"
+
+namespace paddle {
+namespace framework {
+
+PlainNet::PlainNet(const NetDesc& def) {}
+
+void PlainNet::InferShape(Scope* scope) {
+  for (auto& op : ops_) {
+    op.InferShape();
+  }
+}
+
+void PlainNet::Run(std::shared_ptr<Scope> scope, DeviceContext* ctx) {
+  for (auto& op : ops_) {
+    op.Run(ctx);
+  }
+}
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/framework/net.h b/paddle/framework/net.h
new file mode 100644
index 0000000000000..76992e0728290
--- /dev/null
+++ b/paddle/framework/net.h
@@ -0,0 +1,171 @@
+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   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/framework/net_proto.pb.h"
+#include "paddle/framework/op_proto.pb.h"
+#include "paddle/framework/scope.h"
+#include "paddle/platform/device_context.h"
+
+namespace paddle {
+namespace framework {
+using namespace paddle::platform;
+
+// operator's index stored in a network.
+typedef int OpIndex;
+/**
+ * NOTE following codes are some definitions of unimplemented concepts.
+ * We write some basic implementation to make Net compilable. These APIs will
+ * keep updating if the concepts related are implemented.
+ */
+
+struct OpDesc;
+struct OpAttrs {};
+
+class Operator {
+ public:
+  Operator(const OpDesc &def) {}
+  void InferShape() {}
+  void Run(DeviceContext *ctx) {}
+};
+
+/**
+ * @brief Network that manage the operators it has.
+ *
+ * Network is the container and controller of a set of operators, user can build
+ * a real network from a NetDesc which is a protobuf message and use
+ * Network.Run() * to run all the operators in the network.
+
+ * A network object knows all Operators belonging to this network. Variables,
+ * which are inputs and outputs of these operators, are created and managed by a
+ * hierarchy of Scope objects.
+ *
+ * This is the base class of network, all the networks should implement the apis
+ * it defines.
+ */
+class Net {
+ public:
+  /**
+   * @brief Infer shapes of all inputs and outputs of operators.
+   */
+  virtual void InferShape(Scope *scope) = 0;
+  /**
+   * @brief Run the network.
+   *
+   * Run all the operators and return success(true) or not, with all the
+   * variables are located in `scope`. `context` describes the detail execution
+   * environment for ops. `begin` and `end` specify the scope of `ops_` to run,
+   * If no positive indexes are provided, all operators in `ops_` will run.
+   */
+  virtual void Run(std::shared_ptr<Scope> scope, DeviceContext *ctx) = 0;
+
+  /**
+   * @brief Add an Operator according to `def`.
+   */
+  virtual OpIndex AddOp(const OpProto &def) = 0;
+
+  /**
+   * @brief Add optimizer operators acctording to `attrs`.
+   */
+  virtual void AddOptimizerOps(const OpAttrs &attrs) = 0;
+
+  /**
+   * @brief Add backward operators.
+   */
+  virtual void AddBackwardOps() = 0;
+
+  /**
+   * @brief Create a network.
+   */
+  static std::unique_ptr<Net> Create(const NetDesc &def = NetDesc());
+
+  virtual ~Net() {}
+};
+
+/**
+ * @brief a basic implementation of Net.
+ *
+ * PlainNet is a very simple Net, it create a list of operators, and run them
+ * sequentially following the order they added.
+ */
+class PlainNet : public Net {
+ public:
+  /**
+   * @brief Initialize a PlainNet.
+   *
+   * Initialize from  a network describe by `def`. NetDesc is the definition of
+   * a network.
+   */
+  PlainNet(const NetDesc &def);
+
+  /**
+   * Infer all the operators' input and output varialbes' shapes, will be called
+   * before every mini-batch
+   */
+  virtual void InferShape(Scope *scope) override;
+
+  /**
+   * @brief Run the network.
+   *
+   * Run all the operators with the `scope`, if no scope is provided, default
+   * scope will be used instead. If no OpContext is provicded, default context
+   * will be used.
+   */
+  virtual void Run(std::shared_ptr<Scope> scope, DeviceContext *ctx) override;
+
+  /**
+   * @brief Add an operator to this network.
+   */
+  virtual OpIndex AddOp(const OpProto &def) override;
+
+  /**
+   * @brief Add all optimizer operators related into the network.
+   */
+  virtual void AddOptimizerOps(const OpAttrs &attrs) override;
+
+  /**
+   * @brief Add all backward operators related into the network.
+   */
+  virtual void AddBackwardOps() override;
+
+  virtual ~PlainNet() override {}
+
+ protected:
+  /**
+   * @brief Build the network.
+   *
+   * Create operators accordding to `def`, will be called by the constructor.
+   */
+  void BuildNet(const NetDesc &def);
+
+  /**
+   * @brief Add an operator into this network.
+   *
+   * Add a operator which is identified as `type` and has attributes described
+   * in `attrs`, the `inputs` are the keys of readonly input variables,
+   * `outputs` are keys of mutable output variables. An `OpIndex` will be
+   * returned to indicate the offset of the new operator in `ops_`.
+   */
+  OpIndex AddOp(const std::string &type, const std::vector<std::string> &inputs,
+                const std::vector<std::string> &outputs,
+                const OpAttrs &attrs = OpAttrs());
+
+ private:
+  // the operators owned by `Network`.
+  std::vector<Operator> ops_;
+};
+
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/framework/net_proto.proto b/paddle/framework/net_proto.proto
new file mode 100644
index 0000000000000..0779f49fe2a9a
--- /dev/null
+++ b/paddle/framework/net_proto.proto
@@ -0,0 +1,15 @@
+syntax="proto2";
+package paddle.framework;
+
+import "op_proto.proto";
+
+message NetDesc {
+  // network identification
+  optional string name = 1;
+  // operator contains in network
+  repeated OpProto operators = 2;
+  // network type to run with. e.g "plainNet", "DAG"
+  optional string net_type = 3;
+  // num worker always
+  optional int32 num_workers = 4;
+}
diff --git a/paddle/framework/net_test.cc b/paddle/framework/net_test.cc
new file mode 100644
index 0000000000000..a8e31c1497519
--- /dev/null
+++ b/paddle/framework/net_test.cc
@@ -0,0 +1,24 @@
+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   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/framework/net.h"
+#include "paddle/framework/op_registry.h"
+
+#include <gtest/gtest.h>
+
+namespace paddle {
+namespace framework {
+class FakeFC : public Operator {}
+}  // namespace framework
+}  // namespace paddle
diff --git a/paddle/framework/op_registry_test.cc b/paddle/framework/op_registry_test.cc
index 17849ca0191db..ae6b7387129c6 100644
--- a/paddle/framework/op_registry_test.cc
+++ b/paddle/framework/op_registry_test.cc
@@ -119,4 +119,4 @@ TEST(OpRegistry, CustomChecker) {
   for (size_t i = 0; i < debug_str.length(); ++i) {
     ASSERT_EQ(debug_str[i], str[i]);
   }
-}
\ No newline at end of file
+}
diff --git a/paddle/platform/device_context.h b/paddle/platform/device_context.h
index fcef0a5e3058f..160eb4e12060b 100644
--- a/paddle/platform/device_context.h
+++ b/paddle/platform/device_context.h
@@ -36,6 +36,7 @@ class DeviceContext {
 class CPUDeviceContext : public DeviceContext {};
 
 #ifndef PADDLE_ONLY_CPU
+
 class GPUPlaceGuard {
  public:
   explicit GPUPlaceGuard(GPUPlace new_place) : previous_(GetCurrentDeviceId()) {