Abstract: Supercritical carbon dioxide Brayton cycle power generation is a new power generation technology. Moreover, ensuring the corrosion resistance of high-temperature materials is a prerequisite for the operation safety of the equipment. The corrosion behaviors of three alloys P92, Sanicro25, and Inconel625 in 25MPa supercritical carbon dioxide at 600℃ are investigated in this paper. The results are characterized by scanning electron microscope, energy spectrum analysis, X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscope, and glow-discharge optical emission spectrometry. The results show that P92 forms a loose and porous oxide scale, while Sanicro25 and Inconel625 form a dense Cr₂O₃ oxide film. P92 has evident oxide pore formation and carburizing, while Sanicro25 and Inconel625 have Cr depletion. The corrosion resistance and carburizing resistance of Sanicro25 and Inconel625 are significantly better than those of P92. Based on the mechanism of void-induced duplex oxide formation, it is pointed out that the content of Cr is the key to preventing carburizing and ensuring the protective of the oxide scale. The results can provide some reference for material selection and corrosion protection of supercritical carbon dioxide cycle units.