Performance evaluation is an important issue in Web search engine researches. Traditional evaluation methods rely on much human efforts and are therefore quite time-consuming. With clickthrough data analysis, we proposed an automatic search engine performance evaluation method. This method generates navigational type query topics and answers automatically based on search users' querying and clicking behavior. Experimental results based on a commercial Chinese search engine's user logs show that the automatically method gets a similar evaluation result with traditional assessor-based ones. Categories and Subject Descriptors H.3.4 [Systems and Software]: Performance evaluation General Terms Experimentation, Measurement Keywords Performance evaluation, Click-through data analysis