Abstract:The accuracy of the range-finding Radio Frequency Identification(RFID) indoor positioning algorithm will be seriously affected by ranging error. An indoor positioning algorithm based on Multi-antenna Phase Difference Of Arrival(M-PDOA) is proposed. M-PDOA ranging method is employed to measure the distance. The trilateral positioning algorithm is adopted to position the target tag. The simulation results show that the average ranging error of the algorithm is 0.102 7 m, which has a performance improvement by 65.76%; the average error of positioning is 0.180 7 m, which has a performance improvement by 56.67%, indicating that the proposed algorithm can effectively reduce the ranging errors and has high positioning accuracy.