diff --git a/Testing.md b/Testing.md
index 9a5b7df..c744fac 100644
--- a/Testing.md
+++ b/Testing.md
@@ -204,7 +204,7 @@ Once all tests finished, open `index.html` in `coverage/lcov-report` directory t
 If the source code that you developed is all covered by your test scripts, it is ok to send a pull request.
 
 ### Testing editor
-To run a UI test scripts, you need to install chrome browser first. After you install it, run the command:
+To run a UI test scripts, you need to install chrome browser first. Then you need to run `npm install chromedriver@2` to install chromedriver. After you installed it, run the command:
 ```
     grunt test-ui
 ```