The technology of product configuration in a Product Data Management (PDM) system was discussed in this paper. The paper presented the product configuration modeling technology by based on the ‘and/or’ tree of product configuration, the process relation and coupling relation between components, and then, a general model of the product configuration scheme was proposed. The product configuration algorithm based on the product configuration scheme was also introduced and the feasibility from the theory model to the program was proved. The paper also discussed the application of Case-Based Reasoning(CBR) technology in product configuration, and, the emphasis was given towards the similar component search by the Nearest Neighbor(N-N) method. Finally, the product configuration technology was implemented on hydro-generator design process, and the result indicated this technology was valuable to realize intelligentization and automation of product configuration.