The invention relates to a re-utilizing method of sludge in a municipal sewage treatment plant and belongs to the technical field of waste material recycling.The re-utilizing method includes: adding inorganic acid into the sludge to adjust pH to be acidic; adding Fe3+, stirring well, electrolyzing, and performing solid-liquid separation to obtain solid substance; well mixing the solid substance with water, drying, and smashing a mixture into fine powder; sintering the fine powder in a high-temperature furnace to obtain sintered powder; well mixing the sintered powder, potassium titanate whisker and water, adding zinc salt and sodium aluminate, heating, curing, filtering, and drying particles to obtain powder coated by an inorganic compound; well mixing the inorganic compound with other aggregate, and performing ball milling, press-forming and firing.Water-permeable bricks prepared by the method have the advantages of high water permeability and high strength.