The invention discloses an auxiliary clamp for overhauling a high-altitude power transmission line. The auxiliary clamp comprises a connecting mechanism and a turning hook mechanism, wherein the connecting mechanism comprises a bolt, a nut, a sleeve and a supporting frame plate; a T-shaped head is arranged at one end of the bolt, and T-shaped head is clamped with a dual-layer clamping plate of a suspension clamp, while the nut is arranged at the other end of the bolt; the sleeve is arranged in the middle of the bolt in a sleeving manner; the sleeve is fixedly connected with the upper end of the supporting frame plate; the turning hook mechanism comprises a vertical plate, a rotary shaft, a rocker arm and a hook; the vertical plate is fixedly connected with the supporting frame plate; the rotary shaft is mounted on the vertical plate; the left end of the rocker arm is fixedly connected with the rotary shaft while the right end of the rocker arm is connected with the hook; the dual-layer clamping plate is tightly clamped by the T-shaped head and the supporting frame plate by turning the nut; and a hook turning tower is hooked on a power transmission wire on the suspension clamp by turning the rocker arm. According to the auxiliary clamp, the stability, comfort and safety of an operator on the high-altitude power transmission wire are reinforced; the overhauling quality of the high-altitude power transmission line is ensured, and the overhauling efficiency is improved.