The invention discloses a carrier-based launching method of a fixed-wing unmanned aerial vehicle. When preparing to take off, the unmanned aerial vehicle and a tackle stay together at a stop section position of a slide rail; after an engine is started, the unmanned aerial vehicle and the tackle slowly enter a slope section from the stop section of the slide rail, and the attitude of the unmanned aerial vehicle rolls gradually in the sliding process to avoid bridge equipment and prevent wings from colliding; after reaching the top end of the slope section, the unmanned aerial vehicle and the tackle are accelerated to slide down along the slope section by virtue of own gravity of the unmanned aerial vehicle and the tackle and engine thrust, and the unmanned aerial vehicle and the tackle enter a straight section to accelerate sliding; and when the unmanned aerial vehicle reaches a take-off speed, the attitude of the unmanned aerial vehicle levels off gradually, the tackle automatically disengages from the unmanned aerial vehicle, the unmanned aerial vehicle takes off from the tackle by virtue of power of an engine, and the tackle decelerates and stays at the tail end of the straight section of the slide rail. According to the carrier-based launching method of the fixed-wing unmanned aerial vehicle, potential energy of the unmanned aerial vehicle is converted into kinetic energy byutilizing the height difference of a takeoff rail, so that energy can be saved; and the slide rail is installed by using the chord length of a ship, and short-distance acceleration is realized through the engine thrust of the unmanned aerial vehicle.