Abstract: In order to increase the effective area of the polishing film during the magnetorheological polishing process and to control the polishing force generated by the polishing film in real time, the magnetic field lines are mainly concentrated on the edge of the magnet during magnetorheological polishing. The weak magnetic field in the middle of the magnet is not conducive to the formation of the polishing film. The area is greatly reduced, leading to problems such as low efficiency. By chamfering the iron core and opening annular grooves with different edge angles, the edge effect of the magnet is reduced, the magnetic field distribution of 2 mm above the electromagnet is optimized, and the area of the polishing film is increased by the clustering principle. The simulation results show that the magnetic field distribution of the ring groove with the edge angle of75^°is the best, and the center magnetic field strength of the optimized electromagnet is greater than 300 mT, and the maximum magnetic field strength is 420 mT. The gradient of the magnetic field strength above the electromagnet is weakened, from 200 mT before optimization to 80 mT, which is more conducive to the uniform distribution of the magnetorheological fluid. Therefore, the iron core is provided with a certain angled annular groove and chamfer, and the cluster principle is used to provide an effective optimization method for the magnetic field distribution.