Compared to traditional polishing processes, the magnetic grinding method allows relatively easy polishing of theinner surface of complex pipe fittings. For thick slender tubes, the magnetic abrasive grains are subject to small magneticforce and grinding pressure, leading to the low polishing efficiency. Therefore, a new magnetic grinding and polishingmethod is proposed, in which the poles of V-shaped magnet is covered with a mixture of magnetic abrasive grains and oilyslurry, and the magnetic abrasive grains are pressed onto the inner surface of tube in the external magnetic field. This canincrease the grinding pressure of grains on the inner surface and improve the polishing efficiency. The pole-groove V-shapedmagnet is conductive to spontaneous mixing and stirring of magnetic abrasive grains, allowing them continually beingreplaced for inner surfaces polishing of the tubes. Finite element analysis was performed using ANSOFT on the magneticinduction intensity values of inner surface materials polished by magnetic grain only and addition of ungrooved orpole-grooved V-shaped magnets. Theoretically, it was proved that the cutting force was relatively even and produceshomogeneous textures in the inner surface polished by grooved V-shaped magnet. Finally, this method was validated by theexperiment with the SUS304 slender tube.