Abstract: Corrosion perforation of N80Q steel tubing was found in the workover inspection operation of an oilfield. The causes of corrosion perforation of tubing were analyzed by means of macroscopic observation, chemical composition analysis, mechanical property test, metallographic examination, scanning electron microscope and energy spectrum analysis, X-ray diffraction analysis, water quality composition analysis. The results show that the scaling trend of water body was large, and the Cl⁻ mass concentration was high. The temperature gradually increased during the process of water injection, and the pipe wall gradually formed fouling. After scaling, a closed environment under the scale was formed on the inner surface of the tubing, and corrosion gradually occurred under the action of Cl⁻. The corrosion of CO₂ and H₂S in the water was superimposed, and the synergistic effect of various corrosion mechanisms led to serious local corrosion of the tubing, and the local corrosion defects continued to expand, eventually leading to corrosion perforation of the tubing.