A frustum embedded fabricated composite protective structure is provided, including a restraint frame, a back plate, an infill block and a buffer block. The restraint frame is provided with a plurality of mounting holes matching with the shape of the infill block, the restraint frame is arranged on the back plate, the infill block is in a frustum shape. The buffer block and the infill block are installed in the mounting hole of the restraint frame, the buffer block is arranged on the smaller end of the infill block, and the infill block is wedged into the mounting hole of the restraint frame through a wedge surface mating. Because this protective structure is assembled by multiple restraint frames and infill blocks, under the prestress restraint of partition blocks, the damage range after penetration or explosion will be significantly reduced, and it can withstand multiple blows.