Abstract: A power supply apparatus with reverse current protection includes a digital signal processor, a secondary side rectifying circuit, a voltage detection unit and a current detection unit. A plurality of the power supply apparatuses are connected in parallel and applied to a server system. When the voltage detection unit detects that a bus voltage is greater than a predetermined voltage and the current detection unit detects that an output current is less than a predetermined current, the voltage detection unit and the current detection unit inform the digital signal processor that the bus voltage is greater than the predetermined voltage and the output current is less than the predetermined current respectively, so that the digital signal processor turns off the secondary side rectifying circuit to stop outputting power.