The machining mechanism of cluster magnetorheological plane finishing and the action mechanism of dynamic magnetic fields were analyzed. The magnetorheological polishing experiments of dynamic magnetic field on silicon substrate were carried out. Results show that the dynamic magnetic field can make the distorted polishing pad self-repair in time, and that the abrasives have frequent dynamic behavior. It overcomes the shortcomings of distorted pads repairing and abrasive agglomeration under the static magnetic field. The material removal process is stable and the polishing effect is better. Under the dynamic magnetic fields, different polishing methods make big different effect on the polishing results. In multi workpieces synchronous polishing, the high speed self rotation of the large size tool head makes the workpieces have higher line speed, and the abrasives has a stronger effect on the surface defect removal of the mono crystalline silicon substrate. After 5 h polishing, the surface of the silicon wafer is super smooth, and its roughness R_a is reduced from 0.48 μm to 3.3 nm.