The invention discloses a bending device capable of manufacturing rectangular reinforcements with different sizes. The bending device comprises a base box; support columns are fixedly connected to twosides of the top of the base box; a fixed box is fixedly connected to the top ends of the support columns; a first motor is fixedly connected to the bottom of the inner wall of the fixed box; an output shaft of the first motor is fixedly connected with a first belt wheel; the surface of the first belt wheel is connected with a second belt wheel through belt transmission; a rotating shaft is fixedly connected to the axis of the second belt wheel; and the bending device relates to the technical field of reinforcement bending equipment. The bending device capable of manufacturing the rectangularreinforcements with different sizes can change the area sizes of the bent rectangular reinforcements, can produce the rectangular reinforcements with multiple model numbers, is standard in formationof the reinforcements, provides stable support and connection to building frames, can change the torque along with the change of the bent area sizes, and is higher in bending capacity and high in machining efficiency.