Abstract: Corrosion characteristics of X65 steel under four different high temperatures and in NACE solution saturated with CO₂ at 1 MPa partial pressure were investigated by using autoclave,SEM,XRD,weight loss methods and electron-probe micro-analysis.The result showed that in the studied temperature ranges,X65 steel was corroded seriously by CO₂.With the temperature increasing,the corrosion rate of X65 steel had a tendency of decreasing first,then increasing,and the minimum rate appeared at the temperature of 90℃.The main corrosion scale is ferrous sulfide.The effect of CO₂ corrosion made the surface of X65 steel have a feature of point corrosion,pitting corrosion and mesa corrosion.Cl^- excited point corrosion and enriched in the pit of point corrosion,which brought the concentration of Cl^- on part surface of sample different,and accelerated the point corrosion reaction.The corrosion of CO₂ was the result of interaction of multi-factors.