Based on ablation threshold theory, the ablation characteristics of face gear with femtosecond laser are studied and the ablation threshold of face gear is obtained. The theoretical width and depth of femtosecond laser ablation in monopulse and multi-pulse ablation are calculated and simulated. The dynamic recoil pressure mechanism diagram of plasma shock wave is obtained by coupling the change of residual temperature of plasma surface with the change of propagation radius of plasma shock wave with the change of time. The influence of dynamic recoil pressure of plasma shock wave on the morphology of ablated pits, scanning tunnels and ablated planes during femtosecond laser processing are obtained. Experimental results show that the straightness of tunnel decreases with the increase of scanning speed when femtosecond laser scanning the opposite gear. Under the condition of high power, the accuracy of the ablated tooth surface is higher by increasing the spacing between adjacent scanning tracks. These results provide a reference for the influence of plasma dynamic recoil pressure on the surface accuracy of femtosecond laser machining of face gears under different parameters.