The invention relates to a method for preventing a fire aircraft from mistakenly touching an overhead line in dense smoke. The method includes the following steps that: indication devices are installed on a power transmission line between overhead towers; if a pilot drives the fire aircraft to perform an actual fire fighting flight, if the pilot sees a red indication device before, the pilot drives the fire aircraft at a maximum speed provided by a formula 1, and drives the fire aircraft overhead the indication device so as to fly over the overhead line; if the pilot sees a green indication device, the pilot drives the fire aircraft at a maximum rising speed provided by a formula 2, and drives the fire aircraft overhead the indication device so as to fly over the overhead line; if the pilot sees a red indication device and a green indication device simultaneously, the pilot drives the fire aircraft at a maximum rising speed provided by a formula 3, and drives the fire aircraft overhead the indication devices so as to fly over the overhead line; and a flight is repeated. The method of the invention is suitable for realizing a fighting aircraft warning effect in different mission areas in dense smoke. The method has the advantages of low cost and convenient installation and maintenance.