Abstract: Corrosion mechanism of high-temperature and high-chlorine medium transportation pipeline is analyzed. It is pointed out that hole corrosion induced by high-chloridion content, thermogalvanic corrosion induced by hydrogen evolution, compositions of steel material and defects existed in metallographic structure itself, etc. are inherent factors resulting in corrosion of high-temperature high-chlorine medium transportation pipeline. Through comparison experiment with weight loss method, influence of temperature on corrosion rate is analyzed. Result shows that at 90℃ annual mean linear corrosion rate of coupon is 3.13 mm/yr, and at 20℃ is 1.07 mm/yr. It is thus clear that high-temperature environment promotes corrosion progress.