Abstract: In order to study the reasons for corrosion and perforation failure of L245M oil pipeline in service, the microstructure, pit morphology and corrosion product composition of the pipeline were analyzed by metallographic microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results showed that the corrosion products were mainly composed of the compounds of Fe, O, S and Cl. Combined with the on-site environment, it was found that the condensate oil transported by pipeline contained Cl^-, H₂O, H₂S, and CO₂. These substances could corrode the pipeline metal, and the corrosion products could accelerate the corrosion of pipeline. Pitting and eventual perforation occurred in the pipeline in the combined action of these corrosive substances and corrosion products.