Defects are easy to occur during the forming process of inner panel for a car rear door, and the accuracy of parts is difficult to guarantee. Therefore, by analyzing the stamping process of rear door inner panel for car body covering parts, the process scheme adopting the first deep drawing and then the reverse deep drawing and sizing was introduced, and combined with the die structure design of the double-cavity pressing core and the compound sizing tools in the sizing process, the unsolvable problem of cracking caused by the direct deep drawing of part was effectively avoided to reduce the difficulty of die debugging. Furthermore, by applying the process scheme that the trimming and sizing were completed in the same step for the vertical wall of rear door inner panel parts, the die steps were effectively reduced, and the production cycle was improved. In addition, the quality of part was stable, the accuracy of part was qualified, and the flange of part was well matched with the outer plate in hemming, which proves that the layout scheme of stamping process is effective and feasible to provide reference for the development of process scheme of similar parts.