Studied the numerical simulation calculation of laser shock peening of the tooth root of high-strength aerospace gears, the numerical calculation method of laser shock peening pressure was proposed, and the finite element model of laser shock peening of single tooth of aviation gear considering the angle of laser incidence was established. The average value of the residual stress in the width direction at the tooth root was –603.97 MPa calculated by simulation, which was 0.15% different from the average value of the residual stress in the width direction at the tooth root of the gear measured by experiments. Systematic studies were further conducted to investigate the effects of key parameters such as the laser pulse energy, overlap rate and spot radius on the residual stress at the surface and subsurface of the gear tooth root region. The result shows that the average residual compressive stress in the tooth width direction is greater than that in the tooth profile direction at the same depth layer. Increasing the laser pulse energy or the overlap rate can increase the average surface layer residual compressive stress, however, increasing the laser spot radius will reduce the surface layer residual compressive stress average. Increasing the laser overlap rate can effectively reduce the stress fluctuations in the residual stress distribution on the surface, however, an excessively high overlap rate will greatly reduce the efficiency of the laser shock peening process and the actual overlap rate should not exceed 0.8.