The invention discloses a method for applying phosphorus sludge acid in a phosphorite flotation regulator, and belongs to the field of phosphorus chemical industry and mineral separation of phosphorite. According to the method, the sludge acid produced by the phosphoric acid industry is taken as a raw material, and is directly conveyed to a phosphorite flotation regulator groove by using a conveying pump, so as to serve as the phosphorite flotation regulator. After the floating process, the phosphorite flotation index reaches the requirements of producing the phosphoric acid by wet process with a dihydrate method. The method for applying the phosphorus sludge acid in the phosphorite flotation regulator has the advantages of simple process and high applicability, the mineralization coupling technology of the phosphorus chemical industry and mineral separation of phosphorite is achieved, and the method is of great significance on both the resources and the environmental protection.