Abstract: Performance is a crucial factor to the success of a Web application, and performance testing is an important way of ensuring this quality However, due to many uncertainties of Internet and Web users, performance testing of Web applications is more difficult than traditional client/server testing Three performance testing methods for Web are compared A practical, simulation driven automated load testing method is presented with an example The key steps are: ① identify the testing workload and design test cases according to system usage patterns and different client characteristics, ② use suitable tools to develop test scripts, ③ test the application with predefined workload to simulate the behaviors of real users, and ④ collect performance data A template of the performance testing plan is also provided