Abstract: Based on API 581 standard, the quantitative analysis method was used to calculate the corrosion damage coefficient, failure probability and failure consequence of a pressure vessel. At the same time, according to the established risk acceptance criteria, the pressure vessel corrosion risk grade was divided. The results show that this method could achieve accurate quantitative assessment of corrosion risk, and the risk conclusion was also acceptable to the owner. This method has been successfully applied to a platform in Caofeidian, which could be used for reference in other projects.