The utility model discloses a power transmission line vibration-proof device comprising a cable clamp, a steel cable and a hammer body. The cable clamp comprises a primary clamp part and a secondary clamp part which present to be plate-shaped. The surface of the primary clamp part is recessed so that a primary wire slot is formed. The positions arranged above and below the primary wire slot are respectively provided with an upper connecting hole I and a lower connecting hole I. The surface of the secondary clamp part is recessed so that a secondary wire slot is formed. The positions arranged above and below the secondary wire slot are respectively provided with an upper connecting hole II and a lower connecting hole II. The power transmission line vibration-proof device also comprises a fastener I and a fastener II. The fastener I penetrates through the upper connecting hole I and the upper connecting hole II which are matched, and the fastener II penetrates through the lower connecting hole I and the lower connecting hole II which are matched so that the primary clamp part and the secondary clamp part are fixed together, a wire-clamping cavity used for clamping a cable is formed by the primary wire slot and the secondary wire slot through matching, and the surface of the primary wire slot and the secondary wire slot is respectively provided with a flexible antiskid member. The power transmission line vibration-proof device can be connected with the cable in a fastening way so that loosening of clamping can be prevented, shifting, shedding and damage of the vibration-proof device can be avoided, labor intensity of workers can be lowered and safety in power supply is guaranteed.