A method of automatically testing and verifying power management features of a computer system in different modes including Standby, Hibernate, Shutdown, and Reboot is disclosed. After an operator has chosen on an operation menu screen one or more items for executing the power state test and set related numeric values for the chosen items, power state testing functions are executed according to the chosen test items, and the computer system sequentially enters into the power states chosen to test. Auto Resume is set for a timer in a keyboard controller of the computer system to repeatedly execute the chosen power state tests when a time value set for the timer is reached. The method is adapted to test and verifying different power states of the computer system, including Standby, Hibernate, Shutdown, and Reboot, and can be executed without being limited by any computer-specific hardware.