The corrosion resistance property of 316L stainless steel welding joints is improved with the laser shock peening method. The microstructure and the residual stress distribution on the welding joint surface are analyzed. The results show that the residual tensile stress on the welding joint surface treated by laser shock peening is significantly reduced. The electrode potential of the welding joints increases and the diffusion of corrosive media is hindered. Moreover, as a result of laser shock peening, the matrix grain is refined and a large number of slip bands and deformation twins form, which makes the extension of stress corrosion cracks be delayed and improves the corrosion resistance property of 316L stainless steel welding joints.