diff --git a/README.md b/README.md
index d975d3730569dd503b781531a1f2de78de018056..b6ae2beed999d146c64ffc9ee495373d9b77a175 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,24 @@ This project is used to develop the next version deep learning freamwork for mob
 
 [Used model in development](https://mms-mis.cdn.bcebos.com/paddle-mobile/models.zip)
 
+## cross-compilation to android
+
+* NDK is required
+* ANDROID_NDK environment variable is required
+
+```bash 
+sh build.sh android
+```
+
+## build for x86
+paddle-mobile is to run on arm platform. x86 only used to test not arm assembly code. So do not recommend compiling x86.
+
+Now only support osx.
+
+```
+sh build.sh mac
+```
+
 ## Old Version of Mobile-Deep-Learning
 The old version of MDL was I moved to here [Mobile-Deep-Learning](https://github.com/allonli/mobile-deep-learning) 
 
diff --git a/build.sh b/build.sh
index 5761b94a787a111369d8a0057078d3c8df583019..d1603f4a9cd9a36e8e2a92b8cb9124c801f5464b 100755
--- a/build.sh
+++ b/build.sh
@@ -1,11 +1,15 @@
 #!/bin/bash
 
-. /etc/profile
-. ~/.bashrc
-#. ~/.zshrc
-
-build_for_linux() {
-}
+if [ -f "~/.bashrc" ] ; then
+    . ~/.bashrc
+elif [ -f "~/.bash_profile" ] ; then
+   ~/.bash_profile
+elif [ -f "~/.zshrc" ] ; then
+   . ~/.zshrc
+else
+   echo "not found user environment. load /etc/profile"
+   . /etc/profile
+fi
 
 build_for_mac() {
     if [ ! `which brew` ]; then