A testing system for a PSU includes a test chamber and a control device. The test chamber includes a first partition with the PSU accommodated therein and a second partition with an electric load accommodated therein. The PSU is electrically connected to the electric load. The control device includes a microcontroller unit (MCU). The MCU is connected to a setting circuit and a temperature sensing circuit. The setting circuit is configured to set one of predetermined parameters. The temperature sensing circuit is capable of sensing temperature in the test chamber. The MCU is capable of automatically controlling a predetermined temperature in the test chamber and presetting a test time for testing the PSU.