A power management method for a mobile device including a basic input output system (BIOS) and an embedded controller (EC) includes determining whether the mobile device is operated in a direct current (DC) mode, determining whether a loading of an operating system of the mobile device exceeds a predetermined value, adding a flag associated with the embedded controller in a physical memory of the mobile device when the mobile device is operated in the DC mode and the loading of the operating system exceeds the predetermined value, and reading the flag in the physical memory via the basic input output system, to notify the embedded controller to perform a power management process corresponding to the flag.