The general corrosion behavior of five iron-based austenitic alloys (310S, 800H, 904L, and two Alumina-forming austenitic stainless steels containing 2.5 wt.% and 4.5 wt.% Al) was investigated in supercritical carbon dioxide (SC-CO2) at 650 ℃ and 20 MPa. The surface of the materials was treated by grinding and polishing before corrosion to obtain different surface conditions. Based on the influence of surface condition on the surface structure before and after corrosion, the effect of surface condition on the general corrosion of the materials in SC-CO2 was revealed. The results show that the change of surface condition will significantly affect the corrosion behavior of the tested materials in this environment. The corrosion resistance of the materials treated by grinding is more excellent after corrosion for 1000 h. A uniform and continuous protective oxide film is formed, and the total thickness of the oxide film is basically thinner than 1 μm. Compared with commercial austenitic stainless steels, the surface oxide film formed on the Alumina-forming austenitic stainless steels treated by grinding is thinner and shows better corrosion resistance.