diff --git a/Dockerfile b/Dockerfile
index 98f61ba586a681e53b435d592c8e43b1cc964139..136db772cc6a24b8084120fa6bab666bc1eda78e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,13 +10,11 @@ RUN /bin/bash -c 'if [[ -n ${UBUNTU_MIRROR} ]]; then sed -i 's#http://archive.ub
 ARG WITH_GPU
 ARG WITH_AVX
 ARG WITH_DOC
-ARG WITH_STYLE_CHECK
 
 ENV WOBOQ OFF
-ENV WITH_GPU=${WITH_GPU:-OFF}
+ENV WITH_GPU=${WITH_GPU:-ON}
 ENV WITH_AVX=${WITH_AVX:-ON}
 ENV WITH_DOC=${WITH_DOC:-OFF}
-ENV WITH_STYLE_CHECK=${WITH_STYLE_CHECK:-OFF}
 
 ENV HOME /root
 # Add bash enhancements
diff --git a/doc/howto/dev/build_en.md b/doc/howto/dev/build_en.md
new file mode 100644
index 0000000000000000000000000000000000000000..80488a147d2d4b3fa2523503e23343d9bb5be237
--- /dev/null
+++ b/doc/howto/dev/build_en.md
@@ -0,0 +1,83 @@
+# Build PaddlePaddle from Source Code and Run Unit Test
+
+## What Developers Need
+
+To contribute to PaddlePaddle, you need
+
+1. A computer -- Linux, BSD, Windows, MacOS, and
+1. Docker.
+
+Nothing else.  Not even Python and GCC, because you can install all build tools into a Docker image.
+
+## General Process
+
+1. Retrieve source code.
+
+   ```bash
+   git clone https://github.com/paddlepaddle/paddle
+   ```
+
+2. Install build tools.
+
+   ```bash
+   cd paddle; docker build -t paddle:dev .
+   ```
+
+3. Build from source.
+
+   ```bash
+   docker run -v $PWD:/paddle paddle:dev
+   ```
+
+4. Run unit tests.
+
+   ```bash
+   docker run -v $PWD:/paddle paddle:dev "cd/build; ctest"
+   ```
+
+
+## Docker, Or Not?
+
+- What is Docker?
+
+  If you haven't heard of it, consider it something like Python's virtualenv.
+
+- Docker or virtual machine?
+
+  Some people compare Docker with VMs, but Docker doesn't virtualize any hardware, and it doesn't run a guest OS.
+
+- Why Docker?
+
+  Using a Docker image of build tools standardize the building environment, and easier for others to reproduce your problem, if there is any, and help.
+
+  Also, some build tools don't run on Windows or Mac or BSD, but Docker runs almost everywhere, so developers can use whatever computer they want.
+
+- Can I don't use Docker?
+
+  Sure, you don't have to install build tools into a Docker image; instead, you can install them onto your local computer.  This document exists because Docker would make the development way easier.
+
+- How difficult is it to learn Docker?
+
+  It takes you ten minutes to read https://docs.docker.com/get-started/ and saves you more than one hour to install all required build tools, configure them, and upgrade them when new versions of PaddlePaddle require some new tools.
+
+- Docker requires sudo
+
+  An owner of a computer has the administrative privilege, a.k.a., sudo.  If you use a shared computer for development, please ask the administrator to install and configure Docker.  We will do our best to support rkt, another container technology that doesn't require sudo.
+
+- Can I use my favorite IDE?
+
+  Yes, of course.  The source code resides on your local computer, and you can edit it using whatever editor you like.
+
+  Many PaddlePaddle developers are using Emacs.  They add the following few lines into their `~/.emacs` configure file:
+
+  ```emacs
+  (global-set-key "\C-cc" 'compile)
+  (setq compile-command
+   "docker run --rm -it -v $(git rev-parse --show-toplevel):/paddle paddle:dev")
+  ```
+
+  so they could type `Ctrl-C` and `c` to build PaddlePaddle from source.
+
+- How many parallel building processes does the Docker container run?
+
+  Our building Docker image runs a Bash script https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/scripts/docker/build.sh, which calls `make -j$(nproc)` to starts as many processes as the number of your processors.
diff --git a/paddle/scripts/docker/build.sh b/paddle/scripts/docker/build.sh
index 2941662f349baf57d1fe8188e88ce21d5de07750..7bab814ae893a2837a28ef62d0fcb4d74c31c1cb 100644
--- a/paddle/scripts/docker/build.sh
+++ b/paddle/scripts/docker/build.sh
@@ -38,7 +38,7 @@ Configuring cmake in /paddle/build ...
       -DWITH_SWIG_PY=${WITH_SWIG_PY:-ON}
       -DCUDNN_ROOT=/usr/
       -DWITH_STYLE_CHECK=${WITH_STYLE_CHECK:-OFF}
-      -DWITH_TESTING=${WITH_TESTING:-OFF}
+      -DWITH_TESTING=${WITH_TESTING:-ON}
       -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
 ========================================
 EOF
@@ -56,8 +56,8 @@ cmake .. \
       -DWITH_C_API=${WITH_C_API:-OFF} \
       -DWITH_PYTHON=${WITH_PYTHON:-ON} \
       -DCUDNN_ROOT=/usr/ \
-      -DWITH_STYLE_CHECK=${WITH_STYLE_CHECK:-OFF} \
-      -DWITH_TESTING=${WITH_TESTING:-OFF} \
+      -DWITH_STYLE_CHECK=${WITH_STYLE_CHECK:-ON} \
+      -DWITH_TESTING=${WITH_TESTING:-ON} \
       -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
 
 cat <<EOF