The invention relates to a cleaning plant for an ingot mold for mold casting of a round electrode bar and a cleaning method for the cleaning plant. The cleaning plant comprises a cylindrical grinding wheel, an electromotor, a guide dolly and an electric switch which are connected together through a hollow main rod; and the hollow main rod is connected with the guide dolly through a dolly supporting ring, electric wires are arranged in the hollow main rod, and the grinding wheel is connected with the electromotor through a belt, so that the hollow main rod rotates by 360 degrees in a vertical plane where the supporting ring is located, and then the grinding wheel is also driven by the electromotor connected to the hollow main rod to rotate by 360 degrees. The guide dolly comprises two vertical steel plates and four wheels, the hollow main rod is arranged in the dolly supporting ring in a penetrating manner, and the two vertical steel plates are welded to the lower portion of the dolly supporting ring; and two wheels are vertically installed below each steel plate, so that the four wheels are arranged in different planes and are in complete contact with the inner wall face of the ingot mold. By means of the cleaning plant and the cleaning method, residue spots on the inner wall of the ingot mold can be removed, so that it is guaranteed that the inner wall is cleaned, net-shaped fracturing defects are removed, and the quality of mold casting steel ingots is guaranteed.