For the problem of serious wrinkle after drawing of automobile rear floor upper beam, firstly, the drawing process was simulated by software AutoForm, and the cause of wrinkling was analyzed that during the drawing process, the material in the middle of sheet was not fully drawn, and wrinkles were formed at step fillet and sidewall junction zone of product due to shear stress. Next, the process optimization was conducted by software AutoForm. The simulation results show that the wrinkle can be reduced by increasing the radius R of transitional arc in the step surface. However, the edge of step produces a risk of cracking if the R is too large during the subsequent flanging process, and the product is formed well when R is 400 mm. Finally, the effectiveness of the optimization plan was verified through the actual stamping test, and the wrinkle problem is effectively controlled to reduce die costs, shorten production cycles and ensure that the product is delivered on time.