Abstract: The H2S/CO2 environment in the oil shaft was simulated by the home-made high temperature autoclave and the corrosion tests in gas phase of H2S/CO2 and liquid phase of simulated formation water at temperatures of 30-150 ℃ were conducted on the T95 oil tube steel. The effects of the temperature on the steel corrosion rate were studied and the morphology and composition of corrosion products were analyzed. The results show that at the temperatures of 30-120 ℃, the corrosion rate of T95 steel in gas phase and liquid phase both first increased then decreased with the increase of temperature and reached the peak values at 90 ℃ of 0.882, 1.096 mm·a-1 respectively. The corrosion rate increased in the liquid phase slowly while decreased in the gas phase at above 120 ℃. With the temperature increase, the corrosion product in the gas phase changed from flake shape to lump shape and accumulated, while in liquid phase from flocculent deposit to agglomerated accumulation. The corrosion product was composed of Fe, S, O, etc. The corrosion rate was proportional to S content and inversely proportional to O content in the corrosion product films and the iron-sulfur compounds played a corrosion inhibitation role.