In the forging sequences for support shaft, the female die in the process of backward extrusion suffered a wicked stress condition, which was responsible for a short service life. The objective of this paper is to improve the stress condition through optimizing the parameters of multi-layer die, such as the sizes stress rings and shrink-fits. The process of backward extrusion was simulated by DEFORMTM package, and then the node forces on the boundary between workpiece and die were translated into ANSYS. The ANSYS module (APDL) was applied to seek the optimal set of parameters based on the failures of the stress rings in multi-layer die at the same time. In this optimization, a two- and a three-layer dies were taken into consideration for. The optimized parameters will be used as a guideline for the practice application and the strategy used in this study can be extended to the other processes for the support shaft and other extruded products.