Abstract: The stress corrosion cracking behavior of X80 and 16Mn pipeline steels and their welded joint in H₂S solution environment are investigated by three-point and four-point bend loading methods. Stress distribution pattern of the specimen surface is analyzed by ANSYS software. The rule and mechanisms of materials and mechanics influencing SSCC behavior of the pipeline is studied. The result shows that SSCC behavior of pipeline steels with uniform microstructure loaded by bend-beam is controlled by mechanics factor. Although the SSCC behavior can be evaluated by both three-point and four-point bend loading methods, the result obtained by the later method has better consistency than that of the the former. As for evaluating the SSCC behavior of the pipeline welded joint, three-point bend loading method is inappropriate and four-point loading method can be used.