The utility model relates to a transmission line mountain fire monitoring devices based on optic fibre thermometry, its laser lamp -house's signal output part connects the first light signal communication end of light signal conditioning ware, light signal amplifier's first light signal communication end is connected to the second light signal communication end of light signal conditioning ware, light signal amplifier's second light signal communication end is arranged in connecting the composite fiber -optic overhead ground wi optical cable of being surveyed transmission line, data collection card's signal input part connects the feedback electric output end of light signal conditioning ware, data collection card's signal output part connects the bus socket of industrial computer. The utility model discloses simple structure, industrial computer gather the temperature data of optic fibre among the transmission line in real time, and when mountain fire took place, the industrial computer can unusual temperature of real -time recording and unusual temperature position, and the suggestion of reporting to the police.