The invention discloses a clamping power supply, which belongs to the technical field of power supply. For development, overhead medium-high voltage transmission line (including under river cable) is provided with electronic monitoring and instructing equipment, but the power supply of the equipment cannot be obtained from the ground due to high insulation requirements. In the conventional battery power supply mode, energy runs out in a short time period. The clamping power supply comprises a clamping connector connected with the transmission line, a wire and an inductive power extraction device, wherein the inductive power extraction device comprises a magnetizer wounded with a coil, a rectifying circuit and a holding circuit. The power supply can extract power from the transmission lineto supply the power to the electronic monitoring and instructing equipment.