The invention discloses an anti-reburning environment-friendly power transmission line forest fire extinguishing agent. The anti-reburning environment-friendly power transmission line forest fire extinguishing agent comprises the following components in parts by weight: 5-20 parts of ammonium carbonate, 10-45 parts of ammonium polyphosphate, 10-30 parts of sodium silicate, 1-10 parts of a foaming agent, 0.5-5 parts of polyethylene glycol, 1-5 parts of a thickening agent, 4-10 parts of a composite anti-freezing agent and 55-80 parts of water, wherein the foaming agent is selected from one of alkylethoxylate carboxylate, an imidazoline amphoteric surfactant and a biological surfactant; the composite anti-freezing agent is a compound which is prepared by compounding inorganic salt and polyhydric alcohol according to a mole ratio of (1 to 3)-(1 to 9). All the raw materials of the anti-reburning environment-friendly power transmission line forest fire extinguishing agent are environment-friendly materials, so that the fire extinguishing agent is free of fluorine compound, toxicity, smell and pollution; a fire retardant is added into the fire extinguishing agent, so that the fire extinguishing agent is capable of effectively preventing the fire from spreading and is high in fire extinguishing efficiency; the environment-friendly surfactant serves as the foaming agent, so that the fire extinguishing agent is high in foaming performance and is capable of effectively isolating contact between the combustion material and the air and accelerating the fire extinguishing speed; the anti-freezing agent is compounded by the inorganic salt and polyhydric alcohol, so that the freezing point of the fire extinguishing agent is reduced to be -30 DEG C.