Argon ion sputtering alone does not remove completely the carbon remained on the nickel surface. By bombarding the nickel surface contaminated with carbon with an electron beam under a pressure of 10-8-10-9 torr to enhance the adsorption of oxygen on it, we obtain a nickel surface with both absorbed oxygen and carbon. Heating this surface at 360℃ for 45 minutes, we could obtain an atomically clean surface without carbon. The conditions and the possible machanism of removing residual carbon by oxygen are disccused.