The invention relates to the technical field of electric power equipment, and particularly discloses a cable head bolt power-on fastening device. The fastening device comprises a first fastening pieceand a second fastening piece, the first fastening piece and the second fastening piece are both made of an insulated material and each provided with an operation handle and a hexagonal sleeve for being matched with a bolt, and the operation handles and the hexagonal sleeves are arranged at the two ends of the fastening pieces; the first fastening piece and the second fastening piece fasten a bolthead and a nut of a cable head bolt correspondingly, one fastening piece rotates, the other fastening piece keeps static, and power-on rotating operation of the cable head bolt is achieved; and the first fastening piece and the second fastening piece can be replaceable for usage. According to the cable head bolt power-on fastening device, aiming at the cable head bolt loosening situation, under the power-on situation, the cable head bolt is fastened, the electric power maintaining efficiency is improved, and user normal electricity using is not influenced.