Objective The Dongfang gas field in western South China Sea is under high temperature and high pressure condition, with gas reservoir temperature of 141 ℃, CO2 content of 50%, and CO2 partial pressure of 27.9 MPa, and the CO2 in downhole is under supercritical state. The suitable downhole anticorrosion material for this gas field was chosen by the simulation of underground environment corrosion experiment. Methods In this paper, HTHP FCZ magnetic driving reactor was used to simulate the composition and content of underground water ions, and 13Cr steel materials produced by China or Japan were chosen for anticorrosion experiment under supercritical CO2 condition in Dongfang gas field. The chemical composition and microstructure of the metal materials in two different regions were compared. Results The experimental results showed that pitting did not occurr on the 13Cr martensitic stainless steel in either liquid phase or gas phase. The uniform corrosion rate was lower than 0.0013 mm/a. Meanwhile, the corrosion products were uniform and the structure of them was compact. Conclusion Simulated corrosion experiments in Dongfang gas field showed that the corrosion resistance of 13Cr steel in two different regions was similar. Considering the influence of gas flow velocity and sand production in high pressure gas wells, the application condition of 13Cr martensitic stainless steel in supercritical CO2 gas wells was discussed. To reduce the damage to corrosion product film, the flow rate in practical and decrease erosion in tubing should be reduced.