Abstract: The single well pipeline in an oil field was corrupted seriously, and accidents happened frequently. The macroscopic observation, chemical composition analysis, metallographic examination, micro morphology analysis and corrosion product analysis were carried out to analyze the corrosion reason of the perforated pipe. Corrosion pattern of the pipeline material was studied by high temperature and high pressure simulated corrosion test in laboratory. The results showed that the corrosion and perforation of pipeline was mainly caused by CO₂/H₂S electrochemical corrosion in formation water with high salinity and high concentration chloride ion. In addition, poor corrosion resistance of pipeline material 20 steel was also one of the important reasons.