The invention discloses a dual-frequency radio frequency electronic tag which comprises a low frequency antenna used for receiving low frequency signals form an activation source, a low frequency circuit, a high frequency circuit, a high frequency antenna used for sending coded signals to space through high-frequency carrier, and a microcontroller storing identity (ID) numbers of the electronic tag. Programming of the microcontroller comprises the following steps: step one. reading lower frequency information signals and generating intensity identification signals according to intensity of the lower frequency information signals, step two. analyzing and extracting the low frequency information signals and producing signal source codes according to the low frequency information signals, step three. starting timing device interrupt in a time interval, in interrupt status, starting the high frequency circuit, closing the high frequency circuit and opening the low frequency circuit in sequence, step four. quitting the timing device interrupt when time duration achieves the time interval. Distance between the dual-frequency radio frequency electronic tag and a card reader can be measured, accurate positioning is achieved, identification distance is adjustable, and the problem that a plurality of card readers read the same electronic tag at the same time is solved.