A predetermined ID code is set in a server, and a radio frequency identification (RFID) tag is configured on an electronic device. A tag ID code of the RFID tag is received by a reader and then is transmitted to the server. The server is used to compare the tag ID code and the predetermined ID code. When the tag ID code is the same as the predetermined ID code, the server is arranged to transmit an enable signal to grant the access of the electronic device. When the tag ID code is different from the predetermined ID code, the server is arranged to send a disable signal to deny the access of the electronic device.