The work aims to investigate the effects of different magnetic pole arrangement ways of external magnetic poles on grinding quality of internal surface on Al 2024 slender tube during magnetic particle grinding, so as to seek the best way of magnetic pole arrangement. Firstly, basic principle of magnetic particle grinding for slender tube was analyzed theoretically; secondly, magnetic field module of ANSYS software was used to simulate three magnetic pole arrangement ways and obtain different magnetic induction intensity curves. The influences of magnetic pole arrangement ways on grinding effect were investigated by analyzing variation of the curves; thirdly, experimental device was designed, and verification test was applied to the theory and finite element simulation results. The test results were compared by observing roughness and micromorphology of the internal surface. As the angle between the magnetic poles increases from 90? to 180?, the magnetic induction intensity decreased and effective magnetic field areas decreased gradually; the magnetic induction intensity was smaller, so grinding pressure sustained by magnetic particles in magnetic field was smaller, magnetic particles were easily flung out of processing area under the action of centrifugal force. The number of magnetic particles involved in grinding was decreased and grinding quality was reduced. Under the effects of smaller effective magnetic field area, stressed area of magnetic particles was decreased, quantity of magnetized particles was reduced, number of magnetic particles involved in grinding was reduced, and grinding quality was degraded. While the magnetic pole was arranged at the angle of 90?, the result of 10 min grinding test showed that surface roughness decreased most sharply from the original Ra 0.66 μm to Ra 0.12 μm, surface pits and texture defects were removed, surface morphology was uniform, and glossiness was better. During magnetic particle grinding of internal surface on Al 2024 slender tube, adjusting magnetic pole arrangement can improve magnetic induction intensity and effective magnetic field area of the processing area, and then improve the effect of magnetic abrasive particles, promote effective grinding and guarantee better grinding quality.