A modified finite element simulation method was used to predict the surface residual stress and surface deformation of TC17 Titanium Alloy under multiple Laser Shock Peening(LSP). In order to verify the modified method, a bench-mark simulation was performed verified with available experimental results and the predicted results were well correlated with those from experimental data. With the aid of the modified method, the influences of the number of impacts and laser power density have been analyzed. The simulated results show that surface residual stress and deformation increase with the increase of impact number and gradually reach saturation after 3 impacts, nonuniform distribution increases with the increase of impact number. The surface residual stress and deformation increase with the increase of the laser power density.