The invention applies to the technical field of power transmission line maintenance equipment and provides a cable deicing device. The cable deicing device comprises a box body, a processor, a knocking device, an icebreaking unit and a motion device. The motion device comprises a first motor, a second motor, a third motor and a fourth motor. The knocking device comprises a fifth motor, a toggle wheel, a support plate, a support rod, an elastic component, a connection rod and a knocking hammer. The support plate is fixedly mounted in the box body. The support rod is fixedly mounted on the support plate. One end of the elastic component is connected with the support plate. The connection rod is connected with the support rod. The knocking hammer is connected with one end of the connection rod. A shaft of the fifth motor is connected with the toggle wheel. The other end of the connection rod contacts the toggle wheel. The fifth motor is connected with the processor. According to the device, the labor amount of a worker is reduced, and the working safety coefficient of the worker is improved.