Abstract: Acid leaching slag of copper flash smelting dust preparation from magnetic materials was studied for the comprehensive use of copper flash smelting dust. Acid leaching slag of flash smelting dust was processed in different concentrations of hydrochloric acid and lead removal by analyzing the magnetic properties of different processes. The results show that saturation magnetization and remanence increases and coercivity decreases with removed impurities. The optimal acid leaching property occurs when the concentration of hydrochloric acid is 3 mol/L, the saturation magnetization and remanence are 10.965 A·m²/kg and 0.96374 A·m²/kg, and coercivity 3.33×10³ A/m, respectively; acid leaching slag of lead removal, the saturation magnetization, remanence and coercivity are 11.065 A·m²/kg, 0.94 A·m²/kg and 3.228×10³ A/m, respectively.