In this research, the residual stresses in the flange pin peened with ceramic shots are investigated experimentally with X-ray diffraction (XRD) technique and numerically via finite element analysis (FEA) using Abaqus package. The experimental data show that at the surface of the peened flange pin the residual stresses in longitudinal and circumferential direction of the flange pin are all compressive, with the latter much greater than the former in magnitude. Three dimensional FEA models are created for simulating the flange pin surface peened by ceramic shot flow which is generated randomly using the MATLAB program. It is revealed that the residual stresses in the longitudinal, circumferential and radial direction all vary in depth from of the peened surface and are compressive; the maximum compressive stresses occur at the subsurface. The circumferential stress is much greater than the longitudinal stress in magnitude and both are much larger than the radial stress.