diff --git a/README.md b/README.md
index c0b21aac..440e2052 100644
--- a/README.md
+++ b/README.md
@@ -49,13 +49,14 @@ export PATH=${PWD}/Xuantie-900-gcc-linux-5.10.4-glibc-x86_64-V2.6.1/bin:$PATH
 Download source code
 
 ```
-git clone https://github.com/T-head-Semi/csi-nn2.git
+git clone -b 2.2 https://github.com/T-head-Semi/csi-nn2.git
+cd csi-nn2
+git submodule update --init --recursive
 ```
 
 compile c906
 
 ```
-cd csi-nn2
 make nn2_c906
 ```
 
diff --git a/README_CN.md b/README_CN.md
index 3e7aa615..379550e9 100644
--- a/README_CN.md
+++ b/README_CN.md
@@ -48,13 +48,14 @@ export PATH=${PWD}/Xuantie-900-gcc-linux-5.10.4-glibc-x86_64-V2.6.1/bin:$PATH
 下载源码
 
 ```
-git clone https://github.com/T-head-Semi/csi-nn2.git
+git clone -b 2.2 https://github.com/T-head-Semi/csi-nn2.git
+cd csi-nn2
+git submodule update --init --recursive
 ```
 
 编译 c906
 
 ```
-cd csi-nn2
 make nn2_c906
 ```