The present invention discloses a transmission line intelligent cleaning device. The device comprises a winder, a cable and a cleaner. The coil is wound on the winder, and the cleaner is arranged on the cable; and the cleaner comprises a housing, a driven wheel, a rotation shaft, a drive wheel, a main rotation shaft, a single-chip microcomputer, a power battery, a motor, a rotary encoder, a flexible bracing piece, a cylinder, a cleaning brush and a balance weight. The cable is employed to delimit the path of the cleaner, the cleaner is driven by the motor, the motor drives the drive wheel on the main rotation shaft to rotate along the cable to realize automatic advance of the cleaner. The cleaning brush on the cleaner completes the cleaning of an overhead transmission line in the advance process. Workers only need to hang the cable on telegraph poles at two ends of a line and only need to assemble the device so as to very save labor force. The transmission line intelligent cleaning device is internally provided with the flexible bracing piece to adapt the changing of the distance of the cable and the transmission line through regulation of the length of the flexible bracing piece, is not easy to pull and damage the transmission line and is small in damaging of the transmission line.