The invention discloses a fine grain dry separator for weakening magnetic effect loss and belongs to the technical field of magnetic ore separating machines. The fine grain dry separator comprises a lower box, a rack, an upper box, a permanent magnet barrel, a speed reducer, a motor, an ore discharging adjusting device, a gear, a base, an adjusting plate support and the like. The lower box is fixed to the rack through bolts. An axle bed of the permanent magnet barrel is arranged on the rack and connected to the rack through bolts. The permanent magnet barrel is arranged in the upper box and the lower box. A connecting position of the upper box and the lower box is sealed through soft rubber, and connection is achieved through bolts. The surfaces of contact between the permanent magnet barrel and the upper box and the lower box adopt sealing materials for sealing. One end of the ore discharging adjusting device is inserted into an internal seat of the lower box, and the other end of theore discharging adjusting device is arranged outside a lower box body to be connected with an adjusting handle. The permanent magnet barrel is connected with the speed reducer through the gear, and the speed reducer is connected with the motor through a coupler. The fine grain dry separator provided by the invention is simple in structure and convenient to maintain and repair, energy is saved, the service life of equipment is prolonged, and power loss caused by magnetic effect is reduced.