A power supply apparatus with a current-sharing function includes a conversion circuit, a square-wave generating circuit, a resonant circuit, and a rectifier-filter circuit. The conversion circuit has two transformers, and each of the transformers has a primary winding and two secondary windings. More particularly, two secondary windings of the different transformers are electrically connected in series and then the two in-series secondary windings are electrically connected in parallel. The square-wave generating circuit is used to switch a DC voltage into a pulsating voltage. The resonant circuit is electrically connected to the square-wave generating circuit, and having a first capacitor and the primary windings of the transformers. The rectifier-filter circuit has at least two switch components and a second capacitor, and electrically connected to the secondary windings of the transformers to rectify an AC output voltage into a DC output voltage, and the DC output voltage is outputted to at least one output terminal.