Abstract: In view of problems of poor accuracy and dependence on source coordinates of existing underground positioning algorithm, an underground positioning method based on GMapping algorithm and fingerprint map construction was proposed. The signal characteristics of unknown position is matched with signal distribution map, and the optimal positioning coordinates is selected, thereby improving accuracy of the underground positioning; by combining with GMapping algorithm, problem of high maintenance cost of fingerprint map construction process is avoided, and searching and matching efficiency of the algorithm is optimized. Actual test results show that the average positioning error of the proposed method is 57.7 cm, which can meet requirements of underground positioning.