The invention belongs to the electric power installation field, and particularly relates to an overhead wire paying-off vehicle. A wire fastening apparatus comprises a universal joint, a wire fastening rotary shaft and a steel wire rope; the steel wire rope is wound around the wire fastening rotary shaft; the wire fastening rotary shaft is transversely fixed and mounted on a rack behind a gearbox through the universal joint, and the wire fastening rotary shaft and a first power output shaft are mounted on the same straight line oppositely; a brake apparatus comprises a coupler, a second power output shaft, a bearing pedestal, a brake disc, a brake pad and a brake handle; one end of the second power output shaft is connected with the wire fastening rotary shaft through the coupler; the second power output shaft is connected with the bearing pedestal in a matching manner; the bearing pedestal is fixedly mounted on the rack; the brake disc is mounted at one end, connected with the bearing pedestal, of the second power output shaft; the brake pad is wound around the brake disc; and one end of the brake handle is connected with the two ends of the brake pad. By virtue of improvement, real-time braking and mechanical wire tightening function can be realized, and the braking time is shortened by 10.56 times; and meanwhile, manpower is reduced, efficiency is improved by three times, and high safety factor is achieved.