The present invention provides a power-supply apparatus with a current-sharing circuit and a current-sharing method thereof. The power supply with a current-sharing function uses a bus terminal as a current-sharing control interface. A power circuit provides an output voltage and an output current to an output terminal; and it generates a current-sense signal according to the output current. A feedback control circuit controls the power circuit according to the output of the power-supply apparatus. A current-sharing unit generates and outputs a bus signal to the bus terminal according to the current-sense signal. The current-sharing unit also generates and outputs a reference signal according to a reference voltage, the bus signal, and the output current so as to regulate the output of the power-supply apparatus through the feedback control circuit. The bus communication circuit monitors and/or controls the power-supply apparatus.