Abstract: This paper described a wireless-sensor-network based monitoring and positioning system for underground mine.This system regards the condition of ensuring the function of positioning as the basic requirements and uses reasonable fault-tolerant mechanism on the structure of the high degree of disaster.The paper proposed PIR or PIT interior point test method to determine the location area and miner relative position In the ranging phase,using simple and effective calculation method to update path fading model parameters and finally put forward weighted trilateral localization method based on RSSI ranging.The experimental simulation shows that this method effectively improves the personnel positioning accuracy,and proves that it has good fault tolerance.