Abstract: Validity of representation of product data is the key technique and precondition for implementing PDM system．The EXPRESS model of product and its parts was established，which includes product and its version class，product manufacturing relationship class，product assembly relationship class，and product sharing relationship class．Based on EXPRESS model，PDM system was developed which realizes the product structure configuration management and integrated management of product and its related information．Its application in corporation testified the validity of EXPRESS model presented in this article．