Abstract: The macroscopic finite element numerical model and the mesoscopic parametric evolution numerical model of laser shock peening were established. A three-dimensional multi-scale simulation method for laser shock peening was proposed. The distribution law of residual stress, dislocation density and grain size of Inconel 718 superalloy after laser shock peening was analyzed. The Sines fatigue life criterion was modified considering the influence of residual stress and grain refinement caused by laser shock peening on fatigue life, and was verified by tests. The results show that residual compressive stresses no less than 550 MPa within the impact range of the light spot on the sample surface were obtained by simulation; significant dislocation proliferation existed in the surface area, and the local grain size could be refined by about 25%; the simulation was basically consistent with the test results. The fatigue lives predicted by the modified Sines criterion were within 3 times the dispersion band, indicating that the model could predict the fatigue life of Inconel 718 superalloy after laser shock peening.