Due to the complex corrosion environment of CO₂ flooding production wells, there are many corrosion failure cases of tubing in the harsh oil well environment. A comprehensive analysis of failed tubing is helpful to clarify the causes of failure and propose effective protective measures. In this work, the failure behavior and mechanism of N80 tubing in the CO₂ flooding production wells are studied by characterizing their microstructure, mechanical properties, corrosion products and surface morphology. The results show that the sulfide stress corrosion cracking of N80 tubing may be caused by the high concentration of Cl^-, H₂S, CO₂ and other substances in the production well liquids and the combined effect of the existed stresses. Crevice corrosion of tubing may be induced by the galvanic effect in the existed crevices inside and outside of the threaded coupling, of which the synergistic effect with stress can also enhance the stress corrosion cracking susceptibility of tubing. Microcracks initiate in pits with high stress concentration on the thread surface and extend to the inner wall. Cl^- and sulfides are enriched at the bottom of the pits, the crack tip and the bottom of the thread, providing a driving force for crack propagation. Finally, the cracks quickly penetrate the pipe wall, resulting in brittle fracture and failure of N80 tubing.