Aiming at the problems such as thin forming material, easy to have springback and wrinkles of car rear floor, the structural characteristics of rear floor part were analyzed, and it was found that its forming depth was large,and there were a unique “pit” and a large number of punching holes. Then, based on the structural characteristics, the process supplement was designed, and a process scheme was determined to form the “pit” first by two-stage forming and then trimming-punching and flanging-punching. Furthermore, the forming process was simulated by software Dynaform, and the optimal blank holder force was determined to be 425 kN with the maximum thickness thinning rate of 24.489% for part and the material thickening rate in the surrounding wrinkled areas within 10%. In addition,fourteen scrap cutter blocks were proposed to add in the trimming and punching process to make the waste flow in a “two-sided” direction mode, and the scrap cutter and the upper and lower die edge dimensions were designed. Finally, based on the forming process, a real floor trimming-punching die was designed, the trial stamping was performed to obtain the parts in each process, and the forming process was compared. The results show that the process design is reasonable, and the die design is correct. Thus, the qualified products can be produced to meet the the actual requirements of factory.