The utility model discloses a power supply system for power transmission line monitoring equipment, which comprises an electricity taking CT (Computed Tomography) connected with a rectifying circuit,the rectification circuit is connected with a main power supply circuit and a charging circuit through rectification buses. Wherein the power supply unit at least comprises two power taking CTs for respectively obtaining alternating current from a power transmission line; the rectifying circuit comprises rectifying bridges in one-to-one correspondence with the power taking CTs, the rectifying bridges are connected with the corresponding power taking CTs in series, the direct-current positive ends of the rectifying bridges are connected to the rectifying bus, and the direct-current negative ends of the rectifying bridges are jointly connected with the reference ground; the main power supply circuit comprises a main switch and an output converter, the input end of the output converter is connected with the rectification bus through the main switch, and the output end of the output converter is connected with a load; the support capacitor is an electrolytic capacitor, the positive end ofthe support capacitor is connected with the rectification bus, and the negative end of the support capacitor is connected with the reference ground. The output power of the power supply system can beremarkably improved, and the circuit loss is reduced.