The invention provides a method for cleaning active carbon for a supercapacitor during production of the active carbon and relates to a process for cleaning the active carbon for the supercapacitor. The method comprises a precipitation procedure and an acid washing procedure, wherein the acid washing procedure is performed after the precipitation procedure; the precipitation procedure comprises the steps of performing solid liquid separation by natural sedimentation of a flat launder to form a lower layer of carbon liquid mixture and an upper layer of pure liquid, adding hydrogen peroxide into the pure liquid, performing precipitation and purifying potassium carbonate through membrane filtration; the carbon liquid mixture enters the next procedure; the acid washing procedure comprises the steps of adding hydrochloric acid or sulfuric acid into the carbon liquid mixture, performing acid washing treatment, adding pure water, pressurizing and elutriating through membrane filtration until the pH value of the active carbon mixed liquid is neutral or near neutral; furthermore, an elutriation procedure is provided between the precipitation procedure and the acid washing procedure. The method has the beneficial effects that the process is simple and practical; the separation effect of the active carbon and the water is good; the production period is greatly shortened; the water resource is saved; and the labor efficiency is improved.