Abstract: An auto inflate lifebuoy includes a lifebuoy and an air inflation structure joined to the lifebuoy. In the air inflation structure is disposed a base body, thereto is connected a high pressure gas cylinder. A flexible air nozzle is disposed at the outlet of the high pressure gas cylinder. Inside the base body is disposed a top shaft, which pierces through a spring and then has its one end sticking out of the base body and connecting to a press button. The uninflated lifebuoy can be folded and stored away in proper places on board a transportation vehicle such as an aircraft or a ship. It does not take up too much space in normal times and can be quickly accessed in case of emergency. With a press on the press button, the top shaft is pushed to press the flexible air nozzle into the high pressure gas cylinder. The air inside the high pressure gas cylinder is instantly released by the flexible air nozzle and inflates the lifebuoy for use on a person to facilitate emergency escape.