The invention discloses special flattening equipment used after pressure loading is conducted on a hydroelectric rotor iron core magnetic pole. The equipment is composed of a base platform (1), portalframe guiding rails (2), a portal frame (3), a vertical position adjusting box (4), a pneumatic punching hammer (5), a hammer cushion (6), a vertical feeding motor (7) and a longitudinal decelerationbox (8); the equipment is simple in structure, convenient to operate, reliable in performance, automatic operation of flattening procedures of the iron core magnetic core is achieved, the precision of a flattened plane of the iron core magnetic pole is improved, the flattening procedure time is shortened, manpower is saved, and production processing efficiency is improved. Compressed air is adopted as the primary power source, the equipment is clean and environment-friendly, punching strength is controllable, and the equipment has large industrial application popularization value.