The invention relates to a steel plate buck stacker. The buck stacker comprises a frame, wherein width adjusting devices are arranged at two sides of the central line of the frame, and can slide on the frame to be far from or close to the central line of the frame; and a front stacking device and a rear stacking device are arranged under the frame along the operation direction of the steel plate.By the buck stacker, the stacked steel plates are orderly, the production efficiency is high, the steel plate cannot be scratched; and the buck stacker can be changed in a large range according to the length size of the steel plate, and stacking for steel plates in arbitrary specification in the range can be completed.