The utility model discloses a backup wire clamp for a three-span carbon fiber composite core wire. The backup wire clamp comprises a first right-angle hanging plate (1), a second right-angle hanging plate (10), a turnbuckle (2), a first U-shaped hanging ring (3), a second U-shaped hanging ring (9), an extension ring (4), a single plate parallel hanging plate (5), a pre-twisted wire fixed connecting plate (6) and a four-hole type triangular connecting plate (8). According to the utility model, the four-hole type triangular yoke plate and other fittings are connected with the sub-wires (7); Formation of backup wire clamp, when the carbon fiber sub-conductor is broken or the original compression strain clamp fails within a certain range of the outlet of the strain clamp; The backup wire clampcan continue to tension the wires, all split wires do not fall off, safety and reliability of the power transmission line in sections crossing high-speed railways, highways and the like are achieved,and adverse effects on the high-speed railways, the highways and the like are avoided.