The utility model discloses an unmanned aerial vehicle falls over into water and prevents sinking device, include on -off control module, gasbag and aerify the gas cylinder, the on -off control module with aerify the gas cylinder and install on unmanned aerial vehicle's spider, contain integrated altimeter and accelerometer in the on -off control module, the on -off control module links to each other with the switch of aerifing the gas cylinder, it is equipped with four gas outlets to aerify the gas cylinder, four gas outlets pass through thin hose respectively with four airbag connection, four gasbags are two double -phase right, one of them is settled in the spindle side gasbag no. 1, what mainly be directed against is to fall into water in the unmanned aerial vehicle bottom, a pair of gasbag no. 2 is settled in the spindle top in addition, mainly the prevention is to fall into water in unmanned aerial vehicle upper portion. The utility model relates to a practicality is stronger, can realize effectively that unmanned aerial vehicle prevents sinking the function, and the price is suitable, has realistic meaning, can carry out the volume production and reaches the penetration and promotion effect, benefit the society.