Abstract: By stereomicroscopy, SEM, EDS and optical microscopy, macro and micro morphology observation, microstructure examination, and chemical composition analysis were carried out to analyze the failure mode and cause of the contactors in electrical connectors. The results show that stress corrosion cracking(SCC) occurred to the contactors in the media containing Cl^-, resulting in fatigue rupture under vibration stress. The main characters in the failure initial stage of the contactors are corrosion pits and intergranular cracks, and the main characters in the failure crack extension stage are intragranular cracks, cracks branching and fatigue striations. Residual corrosive Cl^- after acid cleaning and coating cracking caused fracture of the contactors.