In recent years, high sulfur and high acid crude oil is widely used in refining device. The sulfur and acid substances in crude oil are extremely corrosive, causing huge security risks to the normal operation of equipment. In this paper, the ultrasonic thickness measurement, macroscopic examination and other means of a set of atmospheric and vacuum unit conducted a comprehensive corrosion inspection. Combined with the scene photographs of the corrosion morphology of gray scale analysis, corrosion scale samples for component analysis can accurately and clearly understand the influencing factors of corrosion occurrence and development. The corrosion rate and the remaining service life of the device in the corresponding position are calculated with the monitoring data of the site. Combined with the operation cycle of the device, the conclusions and suggestions related to corrosion protection are put forward.