The invention discloses an automatic steel plate hooking device. The automatic steel plate hooking device comprises U-shaped steel plate hooks, rectangular lazy arms, a T-shaped support, a lazy arm support and a hoisting ring. The two ends of the front face of the lazy arm support are hung to the hoisting ring through steel wire ropes, and the corresponding rectangular lazy arm is fixed to each ofthe two ends of the bottom face of the lazy arm support through pin shafts. The top end of the T-shaped support is fixed to the center of the bottom face of the lazy arm support through an air pressure pump or a hydraulic pump, and the two horizontal ends are connected with the middle positions of the two rectangular lazy arms through sliding grooves and can slide in the inclined direction of thelazy arms. The upper ends of the rectangular lazy arms are hinged to the lazy arm support through pin shafts, and the lower ends of the rectangular lazy arms are hinged to the U-shaped steel plate hooks through pin shafts. The U-shaped steel plate hooks are horizontally placed and are opposite in opening, and the upper edges of the U-shaped steel plate hooks are longer than the lower edges. According to the automatic steel plate hooking device, hook clamping can be effectively prevented, and steel plates can be rapidly clamped and automatically hooked. By application of multiple automatic steel plate hooking devices, automatic hooking of large-tonnage, long-size and different-thickness steel plates can be achieved.