The invention relates to a production method of a sewage cleanser. The production method is characterized in that hydrochloric acid, water, aluminum ash (slag) or bauxite, and a coagulant aid are mixed according to a certain ratio and are subjected to a reaction. The sewage cleanser produced with the method, which allows dirt and heavy metals in sewage to be removed and the color of the sewage to be removed, can be used for purifying the sewage of industries of papermaking, printing and dyeing, chemical engineering, oil refining, steel making and the like, and has the advantages of less usage amount and low cost.