Many of the domestic PC manufactures and professional PC repair shops are suffering from lack of efficient diagnostic database systems or CAD tools for diagnosis and repair of PCs. In order to solve this problem, a new diagnostic database system for PC maintenance and repair is presented in this paper. We can perform accurate and rapid diagnosis for the PCs with software and hardware troubles by using proposed database system and thus the number of customers who are satisfied with service results are to be increased. Furthermore our research outputs make it possible the experts in PC repair field accumulate maintenance techniques and enhance the reliability of performance evaluated by customers.