Subject heading is one of the access points enabling subject searchers to retrieve the best available materials in the library. This paper uses 48 cloected samples concerning the Tulips system (National Taiwan University Library Information Processing System) to analyze user searching behavior and effectiveness of retrieval under the Chinese Subject Headings. On the one hand, the paper tries to provide some suggestons to improve the structure of the Chinese Subject Headings, and on the other hand to enhance system features of online catalogues.