Abstract: Web server performance evaluation is an approach to understanding how web server reacts under various workloads. This approach contributes to capacity planning and performance enhancements of web server. Discussed in this paper are the principle, approach, and difficulty for evaluating accurately web server’s performance and the solution adopted. A web server performance benchmark, WSBench, is also developed based on web workload characteristics, ON/OFF source model, and browser/server architecture. WSBench generates asymptotically self similar HTTP request sequence measuring web server’s performance as the properties of requests per second, throughput and round trip time, at the levels of 1) HTTPD plus static documents; 2) HTTPD plus dynamic documents （CGI2） without database access; 3) HTTPD plus dynamic documents （CGI） with database access; and 4) combination of 1), 2) and 3). Finally, performance issues are discussed, using the tested performance parameters to suggest performance enhancements that seem promising for web servers.