Abstract: The leakage phenomenon was found in an oil pipeline during the process of line patrolling. The causes of corrosion perforation of an oil pipeline were analyzed by means of macroscopic analysis, chemical composition analysis, metallographic examination and corrosion product analysis, combined with service conditions. The results show that the outer layer corrosion caused by the sealing failure of the circumferential weld anticorrosion joint was the main reason for the corrosion perforation of the oil pipeline, and the Cl^- in the soil accelerated the occurrence of corrosion perforation.