Abstract: A portable power source with removal warning function includes a large battery, a interface, a charging and discharging circuit, a wireless communication module, an alarm module; and a processor. The interface can connect to one of an external power supply and battery (ED battery) of an electronic device. The charging and discharging circuit can charge and allow discharge of the large battery and the charging of an ED battery. The wireless communication module can communicate between the portable power source and the electronic device. The processor can determine whether a distance between the portable power source and the electronic device is within or beyond a preset distance and control the alarm module to sound if the distance is beyond the preset distance.