An auxiliary power supply device for an inverter with a plurality of power modules connected in parallel is disclosed. The auxiliary power supply device includes: a plurality of soft-start circuits, each coupled to a DC port of a corresponding power module; a plurality of distributed auxiliary power supplies, each having an input terminal coupled to the DC port of the corresponding power module; and a centralized auxiliary power supply having an input terminal coupled to an AC side of the inverter, and an output terminal coupled to a DC side of the inverter. By replacing auxiliary power supplies on the AC sides of all power modules with the centralized auxiliary power supply and omitting soft-start circuits on the AC sides of all power modules, the present invention improves system performance in cost, volume, loss, and electromagnetic compatibility.