Abstract: In order to improve the positioning precision of underground mine locomotive further, a positioning algorithm which is based on Received Signal Strength Indication (RSSI) is proposed. Because of the harsh and different environment of mine tunnels, the nearest beacon node is selected as a reference node and the received signal strength and the path loss coefficient at 1 m are solved in real-time. The mine locomotive tracks are assumed as several straight lines that are connected together. The coordinate system included whole mine is established and the equations of the locomotive track is determined. Thus, the positioning method is simplified. The results of simulation show that this has a high positioning accuracy. When the communication radius is 20 m, positioning accuracy can be maintained at 1 m.