The invention discloses a clamping device for plate cutting. The clamping device comprises a base. Rectangular openings are machined in the two ends of the upper surface of the outer portion of the base correspondingly, a set of clamping blocks capable of moving in each rectangular opening is movably installed in the rectangular opening in an embedded mode, supports are fixedly welded to the positions, located below the rectangular openings, of the two ends of the lower surface of the interior of the base correspondingly, N-shaped frames are installed on the upper surfaces of the outer portions of the supports in a bolted mode correspondingly, and rotating motors are fixedly installed in the N-shaped frames correspondingly; circular openings are machined in cross beams of the N-shaped frames correspondingly, bearings are fixedly installed in the circular openings in an embedded mode correspondingly, circular discs are fixedly installed at the rotating ends of the rotating motors correspondingly, and cylinders are fixedly welded to the opposite tangent points of the circumferential faces of the circular discs correspondingly; and rotating rods are fixedly installed on the cylindersin a sleeving mode correspondingly, the other ends of the rotating rods are connected with the lower surfaces of the clamping blocks through hinge pins correspondingly, a controller is fixedly installed on one side of the base, and the controller is electrically connected with the set of rotating motors. The clamping device has the beneficial effects that the structure is simple, and the practicability is high.