For the fine retrieval function of the database system, the facet classification, post controlled retrieval and hyper chaining search are used. Because the class name is also a subject word in the facet classification system, the search is convenient no matter by class or subject word. Meanwhile, there is a net relation among the subject (class) in the facet classification system, the hyper chaining retrieval can be used, so the wider or more specialized search is easy along the chain. For another, there is a line word table in the database,the realization of post-controlled retrieval is easy, therefore, the retrieval effects is guaranteed while the automatic indexing and nature language retrieval are used.