Abstract: During the process of periodic inspection of the heat exchanger, it can be found obvious gap in the surface, which leading to failure of the heat exchanger. In order to investigate the reasons of the failure and keep such incidents from happening again, Metallographic analysis, SEM and electrochemical corrosion perforation are used for E-715 heat exchanger tube sheet weld failure analysis in order to be familiar with its mechanism. It turns out that the heat exchanger corrosion perforation was caused by the electrochemical corrosion. The electrode potential of base metal is higher than that of welding in the service medium which caused the corrosion of welding and final perforation. Meanwhile, the tube medium is a hydrocarbon with a higher carbon content in which the tube surface performed carburization.