Corrosion tests of low alloy steel T24 in supercritical carbon dioxide environment at 550, 600 ℃ and 25 MPa were carried out to obtain the corrosion resistance of T24 steel in supercritical carbon dioxide. It can provide basic data for material selection of supercritical carbon dioxide boiler. The experiments were performed in a static autoclave. The samples were weighed before and after the exposure by using an electronic balance with a sensitivity of 0.01 mg. By means of scanning electron microscope (SEM), X-ray diffractometer (XRD) and Glow discharge emission spectrometer (GD-OES), the oxidation film surface morphology, cross-sectional morphology, physical phase and Element composition distribution in oxide film were characterized. According to the corrosion weight gain curve, the time indices corresponding to 550 ℃ and 600 ℃ are 0.45 and 0.43, respectively, indicating that the corrosion process is controlled by ion diffusion. The surface of oxide scale is mainly composed of granular particle. With the increase of temperature and time, the size of these granular particle gradually increases, and cracks occurred at the surface of the oxide scale at 600 ℃. The oxide film is a typical double-layer structure, the outer layer is mainly Fe3O4, inner layer is mainly composed of Fe-Cr spinel. The enrichment of element C exists on the outer surface of the oxide film, the Fe-Cr oxide film and between the region of inner layer and matrix. With the increase of temperature and time, the thickness of the carbonized layer between the inner layer and the matrix increases. The increase of temperature will accelerate the corrosion rate of T24 steel and the thickness of carbide layer, which will greatly reduce the corrosion resistance and make the oxide film easy to crack or spalling.