In this experiment, Fe(OH)3 and Mg(OH)2 were prepared by using acid leaching filtrate of copper and nickel tailings from Jinchuan as raw materials. During the process, precipitates of Fe3+ (schwertmannite) and Mg(OH)2 were separated from this leaching filtrate according to different precipitation pH values of the metallic ions, and the precipitation mixtures of Al, Co, Ni and Cucan be obtained simultaneously. After that, the precipitates of schwertmannite were put into the NaOH solution at the pH value of 12 and aged at 60℃ for 36 hours so as to transform them into Fe(OH)3. The experiment shows that pH 3.8 and 9.8 were the appropriate pH values to separate Fe3+, Mg2+ and othermetallic ions in the acid leaching filtrate. The results obtained provide a new method for handling tailings in the metallic mine.