Ranging technology based on RSSI (received signal strength indication) is a distance measurement technique with the features of low cost and low complexity. It is widely used in indoor wireless location. Ranging error is relatively large with the impact of NLOS indoor and multipath transmission. For this reason the paper presents preprocessing the received signal strength values with Particle Filter and using BP artificial neural network to measure the distance. According to the result of the experiments, RSSI ranging accuracy and antijamming capability have been significantly improved by this method. Compared with the traditional algorithm, the maximum measuring precision is reduced from 2.56 m to 1.06 m.