Abstract: A power storage and supply method for a power adapter includes determining whether the power adapter is connected to an external power source; if yes, further determining whether the power adapter is connected to an electronic device; if yes, selecting to charge the electronic device or a battery module built in the power adapter; determining whether a physical quantity of the power adapter reaches a first reference value; and, if yes, selecting to charge the electronic device and/or the battery module. The power adapter includes a microcontroller that uses the physical quantity of the power adapter to determine charging sequence, so that the power adapter is not interfered and limited by incompatible device signal control and can be directly used to charge any electronic device while automatically switching among different charging operation states to complete charging of the electronic device and the built-in battery module in increased charging efficiency.