Abstract: The surface morphology and sectional morphology after corrosion were observed by scanning electron microscope (SEM), the composition of corrosion products was analyzed by energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the corrosion resistance of experimental steel was compared by electrochemical workstation, and the effect of welding materials on the corrosion behavior of X65 steel welded joints was systematically studied. It was found that X65 steel, which contains more Cr elements in the welding material, has better corrosion resistance, which is attributed to the fact that Cr exists on the surface of the matrix with Cr(OH)₃ and Cr₂O₃ compounds, which plays a protective role in the matrix. It provides theoretical support and technical guidance for the safe operation of X65 pipeline steel for supercritical carbon dioxide transportation.