The invention discloses a magnetic grinding and polishing device for a large curved surface capable of continuously grinding and polishing a curved surface to obtain uniform surface quality finally. The magnetic grinding and polishing device comprises the following components: a main frame, a front-end supporting side plate, a side plate fixing bolt, a motor, a drive bevel gear, a driven bevel gear, a locating sleeve, a connecting bolt, a fastening bolt, a spindle, a magnetic pole, a grinding material and grinding liquid mixture conveying pipeline, a rotating joint, a magnetic shield, a flange disc, a flange locating bolt, a flange disc, a permanent magnet and a magnetic pole sleeve. The magnetic grinding and polishing device, provided by the invention, has the advantages of high processing efficiency, simple structure, low manufacturing cost and convenience for installation; the magnetic grinding and polishing device has an independent drive motor, convenience for connection with multiple processing equipment or devices, good university and no other external power. The magnetic grinding and polishing device can be widely applied to finish all kinds of curved surfaces, in particular to grind and polish a large-area complicated free curved surface. Technique grinding matched with the device has small temperature rise, high efficiency, difficulty in deformation of a processing work-piece, and no deterioration layer after processing.