The work aims to investigate applicability of different types of casings at high temperature and corrosive environment. With rock core and formation water of LD oilfield as corrosive medium, different types of casings were simulated and evaluated with a HTHP autoclave. Corrosion environment of the oilfield was determined by adopting gas chromatographic technique: MPa and MPa. Corrosion simulation experiments were conducted based on the maximum corrosion gas partial pressure, and corrosion rate of different steels in this corrosion environment was measured, then a prediction mode of long-term corrosion rate was built, long-term corrosion rate of 100H, 80-1Cr and 110-3Cr was 0.24 mm/a, 0.20 mm/a and 0.05 mm/a, respectively. According to the corrosion experiment results and strength attenuation law of heavy oil thermal well casing, strength design of thermal well casing was carried out, and safe life of 80-1Cr, 100H, 110-3Cr was 3.8 years, 6.5 years and 11.2 years, respectively. High temperature will reduce casing strength, and corrosion will change diameter-thickness ratio. Furthermore, cyclic steam injection will accelerate corrosion process, thus cut down service life of the casing. The study results are of guiding significance to material selection of thermal well casing in corrosion environment.