Femtosecond laser precision correction of tooth surfaces has become a new method for complex gear machining. In this paper, the meshing method is used to divide the tooth surface of the face gear into 5 × 9 grid points, and the femtosecond laser incidence angle of each node is measured through the three-dimensional model of tooth surface theory.By analyzing the distribution of laser energy density acting on the tooth surface, the quantitative relationship between the femtosecond laser incidence angle and defocus amount on the tooth surface is determined, the femtosecond laser ablation model of the tooth surface is established, and the variation patterns of the depth of the ablation pit and laser incidence angle are simulated and analyzed.Through experiments, it is found that the maximum relative error between the simulated tooth surface and the experimental tooth surface after ablation is 6.53%, which is within a reasonable range. This indicates that the femtosecond laser ablation model is feasible and provides a technical basis for the femtosecond precision correction of face gear material 18Cr2Ni4WA.