An embodiment of the present disclosure provides a multi-path combined high-low voltage plasma drilling power source and drilling system. The multi-path combined high-low voltage plasma drilling power source comprises a high-voltage DC circuit, low-voltage DC circuits, high-voltage breakdown modules and an upper computer; wherein the high-voltage DC circuit is connected with the low-voltage DC circuits through cables; the low-voltage DC circuits and the high-voltage breakdown modules simultaneously supply power to plasma generators through cables; the upper computer monitors the low-voltage DC circuits in real time; and the same power source comprises a plurality of low-voltage DC circuits and high-voltage breakdown modules.