Abstract: The corrugated plates of a heat exchanger produced by a company cracked which resulted in liquid-crossing phenomenon happening. Chemical composition analysis, metallographic examination and scanning electron microscopic analysis were used to analyze the causes of cracking of the corrugated plates. The results show that the heat exchanger was not stopped according to the regulation during operation and liquid medium was not emptied in time after stopping. At the same time, the content of nickel and molybdenum elements in the corrugated plate material was lower than the standard requirement, and the content of Cl^- in hot side medium running water far exceeded the technical requirement. These factors caused hole corrosion happened at the interface between the junction of gasket and the corrugated plate, and cracks formed by connection of corrosion holes, which eventually led to cracking failure of the corrugated plates.