A method for cleaning a surface of stainless steel includes: a rinsing step, in which a stainless steel tube having carbon residues is subjected to surface cleaning; a disposition step, in which the tube is disposed into an electrolytic tank containing therein a stainless steel cylinder and positive and negative electrodes of a power source are respectively connected to the tube and the cylinder; an electrolyte preparation step, in which phosphoric acid and sulfuric acid are mixed and then added with glycerin to prepare an electrolyte, which is then added into the tank; an electricity supplying step, in which electrical power is supplied to the tube and the cylinder with the current density flowing through the electrolyte, the temperature, and time period of supplying electricity being properly set; and a cleaning step, in which the electrolyte removes carbon residues from a surface of the tube and polishes the surface.