The Wireless sensor networks (WSN) have the distributed network protocol, wireless communications and data processing capability. WSN can real-time monitor, aware and acquire the various environmental or monitoring object information. Using WSN, the coal mine can realize its coal mining, boring work surface, goaf gas, staff orientation, and also overcome these difficulties. When a disaster occurs, WSN can quickly reconstruct the environmental monitoring system to enhance the coal mine safety surveillance system. This paper analyses the characteristics of narrow space in coal mine tunnel, and gives the probabilistic sensing model (PSM) for tunnel narrow space. At the same time, it analyses the relationships among the perceived probability, effective awareness radius and other sensing parameters. For semi-enclosed the narrow space, it gives the node deployment scenarios in coal mine tunnel, when meets the maximum coverage and effective redundancy. This paper lay the foundation for reliability research of WSN in coal mine underground.