Abstract: Naphthenic acid corrosion seriously affects the smooth operation of devices and even leads to major incidents. A high temperature corrosive inhibitor CK356N2C is used at five high temperature places of the distillation unit in SINOPEC Yanshan Co. to lighten corrosion. The results are evaluated by lateral line hydrogen flux detection and iron content analysis. The evaluation shows that the high temperature corrosive inhibitor plays a positive role in the inhibition of naphthenic acid corrosion at high-temperature parts: the hydrogen flux drops by 67.34%～88.82% and the iron content of the second and third vacuum side-stream is decreased to 0.357 μg/g and 0.417 μg/g, respectively, indicating the functions of the corrosion inhibitor.