The development of deep-water gas reservoirs is one of the necessary ways to ensure China’s energy warning line and build an energy powerhouse. However, the downhole pipes of deep-water high CO₂ gas wells have been in service for a long time in high temperature, high pressure, and strong corrosive environments, which are prone to corrosion failure, leading to a decline in pipe strength, affecting the accuracy of predicting the critical value of annular pressure, and increasing the difficulty of controlling annular pressure. To this end, a self-developed high-temperature and high-pressure kettle corrosion experimental device was used to study the corrosion law of downhole pipe columns in deep water high CO₂ gas wells. The attenuation effects of uniform corrosion and pitting corrosion on the strength of the pipe columns were considered, and a residual strength calculation model for the pipe columns was established. A calculation method for the critical value of annular pressure in deep water wells considering different types of corrosion was proposed. The research results indicate that the initial value of the critical value of annular pressure under uniform corrosion is large, but it decreases significantly with age, and the maximum ultimate pressure decreases from 51.88 MPa to 42.40 MPa. The initial value of the critical value of annular pressure under pitting corrosion is small, and the decrease in magnitude with the annual limit is small. The maximum limit pressure value decreases from 22.30 MPa to 21.55 MPa. Considering that the critical value of annular belt pressure under uniform corrosion is mainly affected by the internal pressure strength of the technical casing in the early stage of service, and with the progress of corrosion, it is mainly affected by the extrusion resistance of the tubing in the late stage of service. Considering the critical value of annular belt pressure under pitting corrosion, it is mainly affected by the anti-extrusion strength of the tubing during the whole service period. The research results can provide a reference for the control of annular pressure in deep-water high CO₂ gas wells.