An RFID tag and a method of operating the RFID tag are provided. The RFID tag comprises a memory block that stores at least one predetermined authorization code associated with an RFID reader. In this method, according to the predetermined authorization code and an approval request transmitted from the RFID reader, it is determined by the RFID tag whether the RFID reader is authenticated. When the RFID reader is not authenticated, the RFID tag is controlled to not respond to a subsequent request transmitted from the RFID reader. As a result, the risk that data in the RFID tag may be illegally acquired by an unauthorized RFID reader is reduced.