The thermal effect of femtosecond laser irradiation on the face gear material 18Cr2Ni4WA is studied, and the temperature-stress coupling model of femtosecond laser ablation of face gear is established. The changing process of electron temperature, lattice temperature and thermal stress under different energy densities with multiple pulses is analyzed. The results show that the electron temperature, lattice temperature and thermal stress increase with the increase of laser energy density. Through the comparative analysis of experiment and simulation, the results show that the surface of the ablation tooth surface is residual compressive stress. The ablation depth and pit diameter increase with the increase of laser energy density. The larger laser energy density produces more melt and reduces the quality of femtosecond laser processing. When the energy density is 1.78 J/cm2, the surface morphology of the tooth surface is better. The study could provide a research basis for improving the quality of femtosecond laser micro-ablation face gear.