The designation of this law consultation system, not only considers the situation of the legal profession and based on Chinese Question-Answering System as prototype, but also use searching technology Lucene.net which is a open source project that can preform on many kind of types file. This article also uses ICTCLAS and applies it to the Lucene that makes up for Lucene's lack of word segmentation and mutual information technology to make the law word to be priority search. This paper proposes a method to calculate similarity between question and sentence based on Latent Semantic Analysis (LSA). This method represents the question and sentence with space vector model, under the help of latent semantic analysis theory, and constructs a semantic space, which gets rids of the correlativity between word. And then similarity calculation between question and sentence is implemented in this semantic space. Experiments show that this system has the precision of the operation of the inquiry accuracy and less computation time.