The invention discloses a hot-line work bolt fastening device. The hot-line work bolt fastening device comprises a pneumatic wrench, at least one insulation connecting pipe, an oil water separator and a flexible pipe, the pneumatic wrench is fixed at the front end of the at least one insulation connecting pipe, the pneumatic wrench is provided with an air injection hole and a vent hole, the air injection hole of the pneumatic wrench is communicated with a front end opening of the at least one insulation connecting pipe, the oil water separator is provided with an air inlet hole and an air outlet hole, and a rear end opening of the at least one insulation connecting pipe is communicated with the air outlet hole of the oil water separator through the flexible pipe. The oil water separator is provided with the air inlet hole to be communicated with an air pump, the air pump generates high pressure air that sequentially passes through the oil water separator, the flexible pipe, a second insulation connecting pipe and a first insulation connecting pipe to enter the pneumatic wrench so that the pneumatic wrench is driven to work, an operator can hold the at least one insulation connecting pipe with hands, remotely operates to start the wrench to tightly screw a bolt, hidden danger checking work of power distribution equipment can be finished without power cut, and vapor in the high pressure air can be separated and removed by means of the oil water separator.