The utility model provides a live working bolt tightening mechanism, including pneumatic wrench, at least one insulating connecting pipe, oil water separator and hose, pneumatic wrench fixes insulating connecting pipe front end, pneumatic wrench are equipped with gas injection hole and exhaust hole, pneumatic wrench's gas injection hole with the port is linked together before the insulating connecting pipe, and oil water separator opens has inlet port and venthole, the port is linked together through the hose with oil water separator's venthole behind the insulating connecting pipe. Oil water separator opens has inlet port and air pump to communicate with each other, and air pump production highly -compressed air in oil water separator, hose, the insulating connecting pipe of second, first insulation connecting pipe arrive pneumatic wrench, drives pneumatic wrench and works in proper order, and the operation workman can hand insulating connecting pipe, and remote operation starts the spanner and screws the bolt, under the circumstances that need not have a power failure, accomplishes the work of distribution equipment hidden danger investigation, oil water separator can detach the separation of the vapor among the highly -compressed air.