It is a convenient corrosion test method, which can measure the corrosion rate of various metals in real time with high sensitivity, and the current or voltage applied to the metal surface will not cause irreversible effects. Combined with the characterization method, the failure factors of welded joints are comprehensively analyzed. Due to the complex material properties of dissimilar steel welded joints, the strength of welded joints is low, which becomes the source of stress corrosion cracking defects in joints. The corrosion behavior and influencing factors of T91/TP347H steel GTAW joint in solution containing chloride ions were studied.