Abstract: A simulation study on shot peening strengthening was conducted using finite element software. By writing the INP file of Abaqus, a shot peening strengthening model coupling the finite element method-discrete element method (FEM-DEM) was established. Firstly, the shot distribution in the model is randomly distributed to simulate the actual shot peening process. Secondly, machining stresses are incorporated into the shot peening model to enhance its accuracy. Thirdly, the model's accuracy is validated by comparing it with actual shot peening data. Results show that the simulated deformation is 0.14 mm, while the actual deformation is 0.178 mm, achieving a prediction accuracy of 78.7%. The established simulation model demonstrates good precision. Finally, the influence of different shot velocities on residual stresses was investigated. Results indicate that residual stresses initially increase, then decrease, and finally stabilize as shot velocity rises. This study on shot peening simulation for thin-walled sun gear provides guidance for optimizing the shot peening process, holding significant importance for extending component service life.