The invention provides a method for reducing the alkalinity of red mud by utilizing industrial wastes. The method comprises the following steps of (1) mixing filtered ammonia-nitrogen wastewater and the red mud, and then stirring to obtain a red mud slurry, wherein the mass ratio of the ammonia-nitrogen wastewater to the red mud is 2 to 4:1; (2) carrying out sedimentation and solid-liquid separation on the red mud slurry obtained in the step (1) to obtain a filter liquor and a filter residue; and (3) adding crushed phosphogypsum into the filter residue obtained in the step (3), then adding water, and cultivating at the room temperature so as to obtain the low-alkalinity red mud, wherein the mass ratio of the phosphogypsum to the filter residue is 1 to 5:100. The method provided by the invention has the characteristics of simplicity in process and low cost; and the Bayer process red mud can be treated in a large scale, the treated red mud can be recycled, the storage yard plants are reconstructed, and favorable social benefit and economic benefit are produced.