Abstract: This article expounds the all kinds of conceptions of specificity of retrieval sighs,the conception of retrieval effectiveness and the relation of specificity of retrieval sighs and retrieval effectiveness,and discusses the measure adopted in the three links of the total process of document retrieval for improving the specificity, the fairly control of the specificity and the specificity in the natural language searching.

Key words: Specificity of Retrieval Signs, Natural Language Searching, Document Retrieval