Abstract: Through macroscopic observation, scanning electron microscopy, laser confocal microscopy and energy spectrum analysis, combined with electrochemical test, the causes of corrosion perforation of buried pipeline in a single well in Xinjiang oilfield were analyzed. The results show that the external corrosion of the pipeline was serious, the internal corrosion was slight, and the external corrosion perforation was the main failure mode. The alternation of cold and heat led to the aging and serious damage of the pipeline anti-corrosion layer, and the pipeline body was exposed in the corrosive medium, which was the direct cause of the corrosion thinning and perforation outside the pipeline. CO₂ and O₂ corrosion and bacterial corrosion were important causes of external corrosion of heavy oil thermal recovery pipelines. When the temperature was 60 ℃, the external corrosion was the most serious.