This paper first (describes the current clevelopments of online catalog subject access. In particular, it emphasizes the application of DDC, LCC and LCSH for retrieving subject information through online catalogs. Subsequently, studies in the literature on enhancements to the above subject searching as well as keywords or phrases extracted from the bibliographic record are discussed. Finally, an overall pictures of online catalog which is under the Internet environment and some directions in which the future online catalog should evolve are provided.
