The invention discloses a switch power supply for a chained converter power unit controller, which comprises 7 roads of output isolated with each other by high voltage, thus realizing that working power of the chained converter power unit controller and the IGBT driving power are supplied with power by one switch power supply, therefore, the cost of the power supply is saved. The switch power supply also makes use of the three-element LLC series connection resonant principle to realize the soft-switching process of a power switch pipe by resonant soft switching techniques and also uses parasitic parameters of an isolation transformer as elements of series connection resonant to reduce the consumption of the circuit switch power to the smallest, and the convertion efficiency is relatively the highest; besides, the output power can be regulated perfectly, which reduces the conduction loss of the switch pipes, improves the convertion efficiency of the switch power supply and prolongs the service life of the switch elements.