Abstract: In view of problems that the weighted centroid algorithm based on RSSI would appear error of three-side measuring area selection, only use distances between nodes to measure influence of beacon nodes, but neglect standard deviations of errors in every signal transmission path are different, an underground positioning algorithm of offset error correction based on RSSI was proposed. The algorithm combines with the idea of weighted centroid, and uses RSSI distance model to measure distance between nodes. After obtained the distance information, it can measure the distance error between nodes through probability distribution analysis of standard deviation of the random variables in the ranging error, and then corrects the offset error of the random variables, finally obtains the positioning results with higher precision. The simulation results show that the positioning accuracy improves 19% compared with the weighted centroid algorithm, and the stability of positioning results also has great improvement.