Abstract: Corrosion of gathering transportation pipeline elbow on the ground of an oil field was quite serious, and perforation accidents occurred frequently. Through macroscopic observation, chemical composition analysis, metallographic inspection, scanning electron microscopy observation, energy spectrum analysis and high temperature and high pressure simulated corrosion test and other methods, the causes of perforation of pipe elbow were analyzed. The results showed that the chemical compositions of pipe elbow met technical requirement, and microstructure was normal. The thinning and perforation of pipe were mainly caused by synergistic corrosion effect of CO₂ and H₂S and fluid erosion.