A chain plate flattening device for chain machining comprises a tank body. A first motor is fixedly connected with one side of the bottom of an inner cavity of the tank body. A conveying belt is in engagement transmission with the outer surface of a first gear. A machining mold is fixedly connected with the side, away from the bottom of the inner cavity of the tank body, of a damping device. A roller lead screw is rotationally connected with the side, close to a first supporting rod, of a second supporting rod. A hydraulic device is fixedly connected with the side, away from a supporting table, of a threaded sliding block. A bristle brush is fixedly connected with the side, away from the threaded sliding block, of the hydraulic device. A radiating fan is fixedly connected with one side ofthe top of the inner cavity of the tank body. A driving device is fixedly connected with the middle of the top of the inner cavity of the tank body. The invention relates to the technical field of chain machining. Through the device, materials can be fed automatically, the effect that the overlapping phenomenon of chain plates is avoided is ensured, the machining quality is guaranteed, smooth completion of subsequent machining is ensured, the materials can be discharged automatically, manual operation is avoided, human body safety is ensured, thus, the machining efficiency is improved, and time is saved.