The invention discloses a life buoy used on a ship, belonging to the technical field of ship configuration. The life buoy comprises inflation pumps, a first life buoy ring body, first motors, first ropes, corrugated pipes, inflation bags, a control, a second life buoy ring body, a second rope, an indication lamp, a floating block, a second motor and a vortex propeller, wherein the corrugated pipes are arranged between the first life buoy ring body and the second life buoy ring body; each first motor is arranged on the left side in the corresponding corrugated pipe; one end of each first rope is wound on the output shaft of the corresponding first motor; the other end of each first rope is arranged on the right end in the corresponding corrugated pipe; the inflation bags and the inflation pumps are arranged in the corrugated pipes; the inflation bags are connected with the inflation pumps through pipelines; and the second rope is arranged on the second life buoy ring body. The life buoy used on the ship has the advantages that the size is adjustable; and the life buoy has a propelling function.