A cable thread trimming platform power assisting device belongs to the mechanical field. A first support is arranged. An auxiliary driving motor is arranged on the first support. The auxiliary driving motor is connected to a rotating shaft through a chain and drives a cable reel to rotate through the rotating shaft. A dispersion path of a cable to be sheared in front of the cable reel is provided with a cable thread trimming apparatus. The cable thread trimming apparatus comprises a second support, hydraulic cable shears located on the second support and a corresponding elevating mechanism assembly. The elevating mechanism assembly is provided with a guiding apparatus of the cable to be sheared. One angle of the second support is provided with one rotating shaft. The whole second support can carry out horizontal rotation about the rotating shaft. Through the driving motor, the elevating mechanism assembly and the hydraulic cable shears, mechanized operation to the cable to be sheared is realized so that purposes of assisting and increasing cable shearing efficiency and maximumly reducing operation personnel labor intensity are reached.