A system for testing a PSU includes an input control module, a voltage regulating module, and a load adjusting module. The input control module includes a microcontroller and a plurality of key switches connected to the microcontroller. The microcontroller is configured to receive input instruction from the plurality of key switches and output a control signal according to the input instruction. The voltage regulating module is configured to receive the control signal and generate an output voltage with a voltage value associated with the control signal. The load adjusting module includes a motor coupled to the output voltage of the voltage regulating module. The motor is rotatable in opposite direction to adjust an output current of the PSU. A rotating speed of the motor is in direct proportion to the voltage value of the output voltage.