Abstract: Stress corrosion cracking（SCC） behaviors of welded joint with inconel 690 and 321 stainless steel（including soldering seam, heat-affected zone of inconel 690 and heat-affected zone of 321 stainless steel） were studied through slow strain rate tension（SSRT） test under 100 mg/L Cl^-1without O₂ as well as 100 mg/L Cl^-1 with saturated O₂. Effects of microstructure, chlorine ion and oxygen content on SCC behaviors of the materials were analyzed through SSRT stress-displacement curves and fracture morphology. It is found that the heat-affected zone（HAZ） of inconel 690 is with low probability of SCC under 100 mg/L Cl^-1 without O₂, and showed a certain degree of SCC tendency under 100 mg/L Cl^-1 with saturated O₂, while HAZ of 321 stainless steel is with high probability of SCC under both conditions. The coarse grains of inconel 690 HAZ make against the intercoordination between grains during the plastic deformation, and reduce the strengthening and toughening of grain boundaries, and therefore, increase the SCC tendency of the HAZ.