Abstract: It is of great significance for supercritical carbon dioxide (S-CO₂) power generation technology to study the corrosion behavior and mechanism of alloys in the environment of CO₂ containing doping gas. High temperature corrosion experiment of Super304H and Inconel625 alloy in CO₂, together with corrosion weighting method, scanning electron microscope and X-ray diffraction (XRD) are applied to study the corrosion behavior of the two heat resistant materials in CO₂ doping with SO₂ environment at 750 ℃. The results show that the oxidation kinetic of the materials follows the parabolic law under 750 ℃ CO₂ and 750 ℃ CO₂+SO₂ environment. Inconel625 has a better corrosion resistant ability than Super304H, accompanied by less oxidation weight gain. The initial weight gain of Super304H in 750 ℃ CO₂ is higher than that in CO₂+SO₂, while the weight gain gets larger in CO₂+SO₂ after 120 h. The single Cr₂O₃ oxide scales and the double-layered oxide scales consist of nodular-typed Fe₃O₄ outer layer and FeCr₂O₄ inner layer formed on Super304H after exposure 500 h in two environments. Whereas a stable and dense Cr-rich oxide layer of about 1 µm in thickness grows on Inconel625. The Cr content plays a crucial role to improve the alloy corrosion resistance in high temperature CO₂ environment. High temperature CO₂ doping with SO₂ has the effect of inhibiting carburization during the formation of Cr₂O₃, accelerating corrosion and carburization for iron oxide.