In this paper,the mechanism of femtosecond laser micro-machining surface gear material 18Cr2Ni4WA is analyzed.Based on the dual-temperature model of temperature transfer between photons and electrons,electrons and lattices,the coupling dynamic thermodynamic parameters of photons and electrons,electrons and lattices are established.Through the model simulation analysis,the temperature change process of the electron and the crystal lattice is obtained,and the ablation morphology of materials removed above evaporation temperature is predicted.The femtosecond laser scanning processing experiment on the face gear material shows that as the energy density increases,the pit radius and depth will increase to a certain extent.When the energy density is 1.98 J/cm2,the ablation morphology is better;when the energy density continues to increase to 2.18 J/cm2,a small amount of melt accumulation begins to occur inside the pit,resulting in a certain decrease in the depth of the pit;with the increase of the pulse width,the morphology changes little,but the melt gradually decreases,and the pits tend to be flat;as the scanning speed increases,the depth of the groove gradually decreases and the width gradually increases.The ablation morphology is observed by a three-dimensional ultra-depth-of-field instrument,and the experimental results are basically consistent with the simulation results,which provides a basis for improving the quality of femtosecond laser micro-machined gears.