Magnetic separation is broadly applied to the recycling processing of industrial solid waste, conventional permanent magnetic roll can't separate various magnetic materials from waste residue at the same time. Through theoretical analysis and numerical simulation, this paper matched fan-shaped magnetic steel as disc and developed "Interval alternative process of false magnet", this solved the problem of the magnet assembly. On this basis, a multi-roll permanent magnetic separator was manufactured, by connecting multiple magnetic in series. This equipment can not only get different magnetic products, but also can complete roughing and cleaning assignments, and eased gradation requirements of repairing material significantly. An experiment of choose iron from zinc volatilization kiln furnace slag for a zinc smelter, iron recovery and grade is 76.33% and 62.31%, respectively. This separation roller can also be used in ore, nonmetalliferous ore sorting and powder materials purification, etc.