In this work, an improved equivalent drawbead model is presented to replace the actual drawbead shape. Three-dimensional finite element analysis of the deep drawing process was performed to determine the optimum distribution of drawbead restraining force for the stamping of the joint panel of a gate pillar. The optimum design of the drawbead geometry was executed by means of nonlinear constraint optimization in conjunction with the improved equivalent drawbead model. The drawbead geometry parameters obtained from the optimization design were validated by the achievement of defect-free production panels. The simulation results correspond well with those observed in actual practice, which demonstrates that the restraining force can be reflected effectively by the improved equivalent drawbead model.