Fixed-wing unmanned aerial vehicle unpowered precise landing autonomous navigation method

The invention relates to an unpowered precise landing autonomous navigation method for a fixed-wing unmanned aerial vehicle, and the method comprises the steps: enabling the fixed-wing unmanned aerial vehicle to fly to the sky above the extension line of a current runway in a gliding manner after an engine stops in the flight process of the fixed-wing unmanned aerial vehicle; and carrying out circling height-lowering flight according to the circling radius R, and when the unmanned aerial vehicle descends to a gliding ratio decision height H-j, obtaining the radius change decision height of the last circle of circling height lowering of the unmanned aerial vehicle and the radius of the last circle according to the real height variation of a complete circle, the distance L between the landing point of the runway and the course entry point and the tail end gliding height on the course entry point. And the unmanned aerial vehicle performs last circle circling height lowering according to the radius of the last ci