The invention relates to a gear polishing device. The gear polishing device comprises a rack, support tables are arranged on the rack, clamping blocks are glidingly connected with the support tables,and support springs are arranged between the clamping blocks and the support tables; the gear polishing device also comprises a polishing shaft, polishing teeth are glidingly connected onto the polishing shaft, a cavity is formed in the polishing shaft, an air bag is arranged in the cavity, a downward press rod glidingly connected onto the rack is arranged above the air bag, connecting rods are hinged to two sides of the downward press rod respectively, and the other ends of the connecting rods are hinged to the clamping blocks; a collecting plate is arranged on the polishing shaft, a first magnet is arranged at the bottom of the collecting plate, a falling port is formed in the collecting plate, a baffle is rotationally connected at the falling port, a second magnet is arranged on the baffle, and magnet poles of opposite sides of the first magnet and the second magnet are opposite; a conveying belt and a conveying wheel are arranged below the collecting plate, a third magnet is arranged on the conveying belt, magnet poles of opposite sides of the third magnet and the second magnet are opposite, and the magnetic force of the third magnet is larger than that of the first magnet. Thedevice solves the problem of small application range of traditional polishing devices.