Abstract: In order to reduce the wear amount of punch for hexagonal inter hole forming in an automotive gearbox gear shaft, a hole extrusion model was established researched by software Deform-3D. Firstly, the cold plastic deformation laws for the processed material  of 20MnCr5 alloy steel and the variation laws of hardness and wear coefficient for the hexagonal punch with temperature were studied, and the reliability of the hole extrusion simulation test was ensured. Secondly, the stress and wear conditions of three different forms of hexagonal punches during the hole extrusion process were studied, and the optimal form of the trapezoidal hexagonal punch was determined. Finally, with the aim of reducing punch wear, the process parameters such as punch angle, punch plane diameter, punch transition radius and hole extrusion speed were optimized by orthogonal experiments, and the anti-wear effect of TiAlN coating on the surface of the trapezoidal hexagonal punch was also studied. The research results show that the optimal process parameters for hole extrusion are the punch angle  of 20°, the punch plane diameter of Φ4.5 mm, the punch transition radius of 0.6 mm, and the extrusion speed of 20 mm·s-1. After optimization, the life of the punch is 1.22 times that before optimization. At the same time, the life of the punch with surface coating is 2.20 times that before optimization.