The invention provides a power supply device of a furnace door service vehicle of a coke oven. Four insulators are connected to an L-shaped base via fixed bolts, a sliding contact line is arranged under each insulator and is connected to a carbon plate in a sliding way, the carbon plate is fixed in a U-shaped clamping seat by a clamping plate, the clamping seat is movably connected to upper ends of two swinging rods via connection pins, the two swinging rods are arranged in an inclination way, lower ends of the two swinging rods are respectively connected with rotation shafts at two sides of a spring box body, pre-tightening springs sleeve the rotation shafts arranged in the spring box body, two spring box bodies are respectively welded onto two strip-shaped connection plates, two porcelain bottles are fixedly arranged under each connection plate, and wiring terminals at upper ends of the porcelain bottles are connected with an electric control box via wires. The service lifetime of each sliding contact line can reach 20 years, the power supply device is good in power supply effect and safe and reliable in power supply and is easy to operate and maintain, the running efficiency of equipment can be improved, and the running cost is reduced.