Abstract: The magnetic separation of coarser magnetite is generally adopted by cylindrical magnetic separator. The finer magnetite can obtain a good magnetic separation effect by using a separation device such as a magnetic separation column. However,the cylindrical magnetic separator and magnetic separation column have low separation efficiency for microgranular magnetite. In order to improve the separation effect of fine magnetite,a permanent magnet combined box magnetic separator was developed by innovative use of mechanical swing magnetic system and compound force field. Its main structure is frame,magnetic system,plate,sorting box,the ore and water feed system,transmission system and so on. The magnetic system of the equipment is oscillated on both sides of the sorting box,so that the strength of the magnetic field varies. The stronger magnetic field strength is conducive for the formation of magnetic chain settlement of fine magnetite, and the weaker magnetic field strength is conducive to the flushing water to disperse the magnetic chain and eliminate inclusion. The equipment uses permanent magnet material as magnetic source,magnetic system is stable and energy saving;Compared with the cylindrical structure such as magnetic separation column,cuboid box structure has lower water consumption and uniform magnetic field distribution in the separation chamber. This equipment is suitable for -75 μm magnetite cleaning operation. By combining the separation box and plate,it can meet the requirements of different scale of the separation plant. For magnetite with -75 μm of 96. 50%,a concentrate with TFe grade of 67. 81% and recovery of 96. 11% was obtained under the condition of feeding grade of 62. 83%.