Abstract: The effect of ultrasound on the efficiency of cleaning contaminants from uranium surface with supercritical carbon dioxide (SCCO₂) is studied, and the enhancement of resistibility of uranium against atmospheric corrosion by ultrasonic treatment of uranium in SCCO₂ is explored. The experimental results show that the ability and efficiency of SCCO₂ in cleaning lubricating oil, water, and triethanolamine are significantly increased. It is indicated by AES and XRD analysis for uranium specimen that nickel has been distributed into a certain depth on their surfaces after they are treated with ultrasound in SCCO₂ containing 0.5% nickel tetracarbonyl. TGA reveals that the uranium specimen treated with SCCO₂ (containing 0.5% Ni(CO)₄) in ultrasonic field has a better humid air corrosion resistance than those treated only with SCCO₂.