Gear precision forging is a new method of metal processing. The epoxy resin model is used to simulate the spur cylinderical gear precision forging die. According to the die structure and stress formulation

the radial series cutting slice is used to calculate and analyse the stress field of model. The front ray for one time and oblique ray for two times are used in a a slice. The photoelasticity graph is disposed by numerical method. The stress distribution of die cavity is obtained.