Abstract: The U₃Si₂ bulk material, an advanced nuclear fuel with good thermal conductivity and high uranium density, was prepared by tetra-arc melting in vacuum.The microstructures and depth profile of main impurities were characterized with X-ray diffraction spectroscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy.The results show that the main uniformly distributed impurities were carbon and oxygen.To be specific, a decreasing carbon depth profile possibly originated from oxidation of hydrocarbon in residue gas and carbon surface segregation; and the oxygen depth distribution probably resulted from surface oxidation in argon ion sputtering and oxygen doping or weak oxidation in arc melting of liquid U₃Si₂.