Abstract: The welded specimen of 12Cr2Ni4A stainless steel was shocked by pulse laser shock processing(LSP) as a post weld treatment technology once and twice,and the Erichsen test,surface residual stress and hardness of the welding joints of 12Cr2Ni4A stainless steel were compared before and after LSP treated.The results indicate that the microhardness of the joints is improved by 50% after twice laser shock treated,the tension strength is enhanced from 818.5 MPa to 863.8 MPa,and the position of fracture transfers from hear-affected zone to parent material.The LSP treatment can improve the tensile strength of the joints effectively,and the eliminating of residual compressive stress makes great contributions to the improvement in fatigue properties of welding joints.