The utility model discloses a performance of formation unmanned aerial vehicle is with weighing down water buoyancy device, include organism, support, buoyant device, soak water sensor and controller,the top of support sets up on the bottom surface of organism, and buoyant device sets up on the bottom of organism, soaks water sensor and sets up on the support, and soak the below that water sensoris located buoyant device, buoyant device includes manipulator, actuating member, gasbag and gas bomb, and wherein the gas bomb is equipped with the pneumatic valve, and the manipulator is connectedwith actuating member's one end, and actuating member's the other end and pneumatic valve are connected, and the air inlet of gasbag is connected with the gas outlet of gas bomb, the controller is respectively with soak water sensor and the manipulator is connected. In this way, the utility model discloses a performance of formation unmanned aerial vehicle is with weighing down water buoyancy device can protect unmanned aerial vehicle when the unmanned aerial vehicle accident falls over into water to maintain unmanned aerial vehicle's normal use.