Product development is an integrated and interactive process. This paper proposes that there are three domains in the process of product development, i.e. product domain, organization domain and process domain, viewed at three angles of product, organization and process of product development. It is proposed that product domain is the core of these three domains, and then gets interrelations within them. The method of classifying parts and components in product domain is put forward, and the corresponding organization domain and process domain are put forward. The direction of parts and components domain is pointed out. In the end, this paper gives an example applied to the method in a motorcycle enterprise.