A dissimilar metal branch pipe joint on primary pipe in a nuclear power plant has leaked,which had certain impact on nuclear safety and caused huge economic losses. The main cause of the leakage is stress corrosion cracking（SCC） due to excessive residual strain on the stainless steel side of the weldment. In this paper,the welding residual stresses of joints with different welding materials, heat input and structures are analyzed by finite element method. It is found that the residual strain near the bond line on the joint stainless steel side could be effectively reduced with the improvements such as replacing 82 filler metal with 309L,reducing heat input and adding a carbon steel transition section,thus the SCC susceptibility of joint can be mitigated.