The invention relates to a method of production of PSAF from nickel slag and red mud. The method consists of: firstly drying red mud and nickel slag and performing crushing; then, mixing the red mud powder with a sulfuric acid solution, and conducting pumping filtration to obtain a mixed solution containing Al and Fe, mixing the filter residue with NaOH and conducting pumping filtration to obtain a sodium silicate solution, letting the filter residue enter a nickel re-extraction process, and adding hydrochloric acid into the sodium silicate solution to obtain a polymeric silicic acid solution; and finally, mixing the mixed solution containing Al and Fe with the polymeric silicic acid solution, and carrying out heating, stirring and standing ageing to obtain PSAF. The PSAF can be applied to wastewater purification test, and the CODcr and chroma removal rate of sewage both reach 90% or more, and the residual turbidity is about 0. The PSAF prepared by the method provided by the invention has good sewage purification effect, and nickel in the nickel slag can be enriched for re-extraction. Therefore, the method provides a green and environmental protection approach for cyclic utilization of the two industrial solid wastes, and produces good economic and social effects.