Femtosecond laser micro machining of face gear material 18Cr2Ni4WA is an advanced manufacturing method for removing materials. In this paper,according to the relationship between the depth and width of ablation pits and laser energy density,the ablation threshold of materials and the factors affecting the overlap ratio are obtained. Considering the inter temperature induction effect between gear material components and the accumulation effect of multi pulse laser,the energy complex coupling model of the material is established. By changing the laser energy density and the number of pulses,the change rule of femtosecond laser ablation pits and tooth surface topography is studied. It is concluded that the number of pulses has little effect on the ablation effect,and the laser energy density is 1.730 J/cm2,the laser power is 1.9 W,the pulse number N=3000,and the best ablation effect can be obtained,and the optimal actual ablation surface depth is 17.604μm.