The invention relates to a cluster-type large-plane polishing device based on a magneto-rheological effect. The device comprises a workpiece, two positioning wheels, a plurality of polishing wheels, magneto-rheological fluid, abrasive particles, permanent magnets, bearing pedestals, ball bearings, a rotation shaft, a motor, a high-pressure spraying head, a pump, a scraping block and a container; the radius of the positioning wheels is 2 mm larger than that of the polishing wheels, the side surfaces of the outlines of the positioning wheels make direct contact with the surface of the workpiece, the positioning wheels and the polishing wheels are fixed to the rotation shaft, the two ends of the rotation shaft are connected with the bearing pedestals through the ball bearings, and the rotation shaft is driven by the motor to rotate; the polishing wheels are distributed according to the size of the workpiece, each polishing wheel is provided with four permanent magnets, the magnetic poles of each permanent magnet are arranged in a heterospolar mode, and the magnetic poles of every two adjacent polishing wheels are arranged in a homopolar mode; the magneto-rheological fluid and the abrasive particles form polishing fluid, the polishing fluid at an outlet b of the container is drained to a polishing area through the high-pressure spraying head by means of the pump, the polishing fluid on the surfaces of the polishing wheels is recovered into the container from an inlet a through the scraping block, the container is of a concave structure, an opening of the recovery inlet a is large, and an opening of the outlet b is small.