The work aims to explore the influence of compound magnetic pole magnetic circuit on the surface quality and surface roughness value of the workpiece in magnetic abrasive lapping and solve the problem that the traditional magnetic abrasive lapping in abrasive particles far away from the processing area due to the smaller magnetic force, which makes the workpiece surface quality is low. Firstly, the lapping mechanism of the composite magnetic pole magnetic circuit method is analyzed, and the influence factors are analyzed through the force analysis of the abrasive particles in the processing. The equivalent magnetic circuit method is used to calculate the magnetic induction intensity of the processing area formed by the three magnetic circuits. And then Ansoft Maxwell software is used to compare and analyze the magnetic gradient simulation of the three magnetic circuits, comprehensively analyze and evaluate the effect of the influencing factors, so as to lay a theoretical foundation for the test. Finally, the surface roughness and surface quality of the workpiece before and after lapping with different magnetic circuits were measured and recorded by surface roughness measuring instrument and super deep scene 3D microscope. Compared with traditional lapping, the magnetic induction intensity in the magnetic circuit of composite magnetic pole is larger, and has obvious and symmetrical magnetic field gradient effect. The workpiece surface roughness value is reduced from 0.10 μm to 0.06 μm, and the improvement rate of surface roughness is increased by 40%. The surface lapping quality of the workpiece is better. The results show that the composite magnetic pole magnetic abrasive finishing process can remove the scratches, pits and spots on the surface of the workpiece, which makes the surface of the workpiece smooth and has mirror effect. Compared with the traditional lapping process, it has obvious advantages of good quality and high efficiency.