Abstract: The implementation of class cases retrieval aims to strengthen judges' hearing a case according to the previous requirements, to further the unification of the application of the law and improve the efficiency of trials. However, after all, the category search system is still in its infancy, the basic theory and comprehensive supporting implementation plan are not yet mature, so this paper will be aimed at the object, scope, method, effectiveness and how to apply in the criminal trial work and other difficult issues in-depth demonstration, which is significant to perfect class cases retrieval in criminal judicial work.