A power supply test system for testing the reliability of a power supply includes a controlling input module, a signal collecting module, a signal input module, an alarm module, and a display module. The controlling input module inputs a time signal and a test signal in the signal collecting module. The signal collecting module turns on the power supply according to the test signal. When the power supply is turned on, the power supply outputs a power on signal, the signal collecting module records the time the test starts. When the power supply breaks off, the power supply outputs a power off signal, the signal collecting module records the time the power supply breaks off and outputs an alarm signal. The alarm module receives alarm signal and alarms to indicate the test is over. The display module displays the time the test starts and the power supply breaks off.