The invention discloses a fire scene positioning method and system based on an unmanned aerial vehicle. The method comprises the following steps: acquiring data of physical object markers or special buildings arranged in multiple places around the fire scene to serve as markers, and establishing a self-determining coordinate system; manually pointing out two of the markers from pictures shot by the unmanned aerial vehicle, combining the click positions and an attitude angle to calculate the position of the unmanned aerial vehicle under the self-determining coordinate system so as to perform unmanned aerial vehicle positioning; manually pointing out the position of the same key point according to the two pictures shot by the unmanned aerial vehicle, combining the click position, the attitude angle and two shooting positions of the key point, calculating the position coordinate of the key point in the self-determining coordinate system, and completing positioning of the fire scene relative to the key point, wherein the position of the unmanned aerial vehicle is the shooting position. According to the method disclosed by the invention, the fire scene is accurately and rapidly positioned, the key point and buildings are marked, intuitive site conditions are provided for fire scene commanders, the fire scene commanders are assisted in making disaster relief tactic decisions, and theefficiency is greatly improved.