Abstract:RFID is one of the crucial technology of the IOT (Internet of things), and it has been applied to the fields of manufacture, logistics, public security, and etc.. Active RFID is one of RFID, and the striking features of active RFID are low power consumption, stable signals, long-distance reading and anti-jamming ability. Therefore, active RFID is widely used in the areas of long-range identification of personnel and vehicles and Real Time Location System. In the various application of active RFID, the judgement of direction of movement is a vital technical matter. This paper puts forward a new method to judge. In other words, with several directional antennas, it forms several reading areas, picks up events of the tag entering or exiting and then realizes the judgement of direction by the order of events。In this way, we could not only judge the direction of movement of tags accurately, but also judge other complicated logic, e.g. the midway return of tags.