The invention provides a radio frequency identification (RFID) tag. The RFID tag includes a receiving module, a judging module, and a jamming module. The judging module includes a first judging unit and a second judging unit. When a jamming function of the RFID tag is activated, the first judging unit judges whether a request signal received by the receiving module contains a reading command. If a judgment result of the judging module is positive, the second judging unit then judges whether an authorization code of the reading command is valid. If either the judgment result of the first judging unit or the second judging unit is negative, the judging module controls the jamming module to generate a radio frequency (RF) jamming signal.