A power management method is applicable to an electronic device having GPS navigation software and a GPS module for executing the navigation software. First, the data storage power (i.e. the RTC power) is enabled when the electronic device is powered on, and whether the electronic device receive an external power is detected; if yes, the master power (i.e. the RF power) is enabled and the GPS module is enabled to perform an initialization process and continue detecting whether the electronic device receives an external power; it no, the master power is disabled and detecting whether the electronic device receives an external power continues. Compared with the prior art, the power management method of the present invention, by managing powers installed in the electronic device and corresponding to the GPS module, increases the possibility for the navigation software to enter the hot start mode, and advances user's convenience.