An energy-saving power supply apparatus includes a bridge rectifier, a diode bypass circuit and a control circuit. The diode bypass circuit is electrically connected to the bridge rectifier. The control circuit is electrically connected to the diode bypass circuit and the bridge rectifier. The bridge rectifier includes a plurality of diodes. After the control circuit receives a power start signal, the control circuit is configured to control the diode bypass circuit, so that a part of the diodes are bypassed to save energy.