Abstract: SAF2507 ferrite-austenite duplex stainless steel surface was treated by shot peening. Effects of shot peening on surface roughness, microstructure and residual stress of the tested steel were studied by X-ray stress analysis and diffraction line-profile analysis. The results show that after shot peening, there were fewer dislocations in ferrite phase, a large number of dislocations in austenite phase, and the surface roughness of tested steel increased. The surface grain of the tested steel was refined, the micro-distortion and dislocation density increased. High residual compressive stress was introduced in the near surface layer of the tested steel by shot peening. The maximum compressive stress in austenite phase and ferrite phase appeared in the subsurface layer, with values of 915 MPa and 763 MPa, respectively.