Abstract: Corrosion detection technologies such as fixed thickness measurement and hydrogen flux testing were used to monitor the corrosion of 4 atmospheric and racuum distiuation units from 2008 to 2010 for about two and a half years. The monitoring results were compared with the database of API 581. The results showed that material 20# had obvious corrosion when the temperature was over 220 ℃. In the high temperature feed line of coking unit made of material Cr5Mo mainly, some of the pipelines were thinned by corrosion significantly. Corrosion of pipelines with material 304/321 was slight when the temperature was below 288 ℃. Serious corrosion occurred on material 304/321 when used for higher temperature and high fluid velocity transfer line. Material 316L had good anti-corrosion capability in processing high acid crude oil, even the corrosion of transfer line was slight. The corrosion rate of transfer lines with material 316L was about 0.1 mm·a-1, and small part of which was 0.1~0.2 mm·a-1.