The utility model discloses an insulation rope brake control device for power transmission overhead line live-line operation. The insulation rope brake control device includes a fixing base and two insulation grinding cores, the two insulation grinding cores are parallelly connected at the outer side of the fixing base, the outer ends of the two insulation grinding cores are fixed by the same one positioning plate, and the fixing base, the insulation grinding cores, and the positioning plate form an enclosed door structure. The fixing base of the device clamps the two edges of an angle-iron cross beam to connect into one body, an insulation rope is wound on the grinding cores to be large in contact area, so that enough friction force can be generated to control the descending speed, and the safety is improved. Meanwhile, the enclosed door structure can prevent the insulation rope from jumping, so that the stability of the insulation rope during movement is improved, and the safety is also improved. Due to the contact of the insulation rope and the insulation grinding cores, the insulation performance of the insulation rope can be guaranteed, and the service life of the insulation rope can be prolonged.