Abstract: In the traditional expert system, the realization of the control of the inference procedure is programmed. In this paper the authors introduce an expert system of inference procedure led by relational database technique, that is, the inference control strategy of the expert system for diagnosing schizophrenia. In the expert system, the authors use the database method to store and manage the control information of inference procedure, so that data processing for the control strategy is lealized. The control strategy can be easily adjusted if we use foe database method in inference procedure of the expert system. Moreover, it will greatly cut down the program space, and raise the efficiency of system motion. It offers a feasible plan for the structure design of the expert system.