The work aims to combine magnetic abrasive finishing with single chip microcomputer control electromagnetic field to improve quality and service performance of internal surface irregular bend pipe. According to theory of static magnetic field and model of magnetic particle trajectory, the optimum magnetic path was designed by controlling electromagnetic field through current and the rotating feed magnetic field was formed to improve the electromagnetic grinding efficiency. The spiral machining track of the magnetic particle was formed by spiral distributed electromagnet to avoid the interference on the elbow bent in rotating feeding process space of magnetic support and improve the processing efficiency by processing in multiple stages. The track of magnetic track was analyzed by the theory of static magnetic field and the feed path of the spiral grinding of the auxiliary magnetic pole in radial direction of bend pipe was studied. For internal surface polishing of SUS304 faucet, when the average particle size was 250 μm, the amount of grinding fluid was 8 mL and the speed was within 800～1000 r/min. After grinding of 50 min, the roughness value on internal surface of workpiece dropped to Ra 0.38 μm from Ra 1.1 μm. The magnetic grinding based on the auxiliary magnetic pole under the rotating feeding electromagnetic field has obvious effects on improving the internal surface quality of the bend pipe and the service life.