The performance guidelines such as the response time and the connection unsuccessful rate are the key factors to determine the quality of a Web application. To calculate these performance guidelines quickly, show result to users with visual way and reduce the cost of testing tools, a performance testing tool ASTD aiming at web application is developed. ASTD provides many functions such as testing plan management, testing plan execution and testing report producing. Based on simulating users’ behavior, an E-government system developed for Fangshan is tested by the ASTD. By analyzing the test results, the bottlenecks of the system were found and the performance of this system was optimized.