diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..38b7159
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "binding/ip2region4php"]
+	path = binding/ip2region4php
+	url = https://git.oschina.net/monsterkiller/ip2region.git
diff --git a/README.md b/README.md
index aea5a77..23257b3 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ ip2region - ip到地区的映射库，妈妈再也不用担心我的ip定位。
 
 **4. 多查询客户端的支持，0.0x毫秒级别的查询**
 
-已经集成的客户端有：java, php, c, python。
+已经集成的客户端有：java, php, c, python，PHP扩展。
 <pre>
 提供了两种查询算法，响应时间如下：
 客户端/binary算法/b-tree算法：
diff --git a/binding/ip2region4php b/binding/ip2region4php
new file mode 160000
index 0000000..fc48495
--- /dev/null
+++ b/binding/ip2region4php
@@ -0,0 +1 @@
+Subproject commit fc4849567b3af642f544a804ff6f411cc83862b6