The ship-borne orbital PY22 type down-the-hole hammer drilling rig is specially designed and produced according to the submarine rock condition of Victoria port in Hong Kong. The drilling rig adopts dual-drive reducer to drive the down-the-hole hammer to break the submarine rock through the air hole in the center of the power head. The whole machine is composed of upper plate, walking beam, movable wellhead plate and ship surface track, which is driven by hydraulic brake to complete walking.