The invention relates to the technical field of power equipment, and discloses a cable fixed-length winding auxiliary device for a power transmission line. The cable fixed-length winding auxiliary device comprises a support, a first rotating shaft is movably connected in the support, a first gear is fixedly connected to the exterior of the first rotating shaft, second gears are engaged with the exterior of the first gear, a second rotating shaft is fixedly connected in each second gear in a sleeved manner, a first rotating disc is fixedly connected to the exterior of each second rotating shaft, a pole N is fixedly connected in each first rotating disc, a pole S is fixedly connected in each first rotating disc, a connecting rod is movably connected in each first rotating disc, and a secondrotating disc is movably connected to the exterior of each first rotating disc. Through interaction among the support, a shell, the first rotating shaft, the first gear, the second gears, the first rotating discs, the second rotating discs, the connecting rods, the poles N, the poles S, balancing weights and first springs, a winding roller cannot generate any influence on normal winding during normal winding, and the situation that use of the device influences normal winding, and consequently storage and transportation of power transmission cables are influenced is avoided.