Abstract: According to the special environment and requirements of underground personnel positioning in coal mine, the personnel positioning system was presented, which depended on the micro-electro-mechanical-system inertial measurement unit based on the pedestrian dead reckoning. It obtained data by the accelerometer, the gyroscope and the magnetometer in MEMS, the key technology problem was solved about the sensor drift error combined with the particle filter research, thus the underground positioning accuracy was improved. The experiment result showed that the average error was less than 2 m in 100 meters, which could satisfy the underground personnel positioning requirement.