Provided is a method of protecting files of an electronic device. In the method, a pre-setting return information is read in a wireless communication tag; a setting interface is provided; the files of the electronic device is selected through the setting interface; a predetermined protection time period and a pre-setting return information are set through the setting interface; wireless communication signal having a fixed frequency is transmitted by the electronic device; the selected files are encrypted if no pre-setting return information is obtained by the electronic device from the wireless communication tag; the selected files are deleted upon the condition that the selected files are encrypted for the predetermined protection time period.