In order to meet the design requirements, the wet shifting clutch was designed based on secondary development of Pro/E. The basic principle of parametric design and the system composition of Pro/Toolkit application program were introduced. The three-dimensional template of wet shifting clutch was established. The VC++6.0 programming platform was utilized. The application program interface was set up by using the synchronous mode of Pro/Toolkit. The regeneration of wet shifting clutch was completed. The parametric design about the key sizes in the key parts and assembly relationship of the wet shifting clutch were realized. The convenient design of wet shifting clutch was achieved. The effective method could be provided for the parametric design of other complex parts.