Transmission line live working insulator from adaptive type closed fixture, it is mainly including using the body of the preceding card on the steel cap and the back card body around the insulator respectively to and block qian kagai and the houkagai that the body matches with the preceding card body and back respectively, the preceding card body and qian kagai, the back card body after and kagai respectively the round pin axle through one end meet and be in the same place, just the preceding card body is provided with the same radial half -circular arc groove respectively with qian kagai, the back card body and back kagai's centre to be formed with the circular bayonet socket that can block on the insulator steel cap in the middle of when the card body and qian kagai, the back card body and back kagai hinge into an organic whole respectively in the front respectively it has the joint bolt of taking fixation nut to meet through the round pin axle respectively on the preceding card body and hou kagai, the back card body and back kagai's the other end, in the preceding card body and hou kagai, the back card body and back kagai's the circular bayonet socket in centre, be provided with big inclined plane towards the another side and form one side reducing toper bayonet socket greatly from one side at least.