Serious geological hazard such as the roof fall rib spalling closure deformation of the cavity can exert bad influence to mine, even threaten human life. The traditional monitoring ways have some disadvantages, which are difficulties in obtaining data of the cavity, monitoring the unmanned cavity and calculating volume of the cavity accurately. To solve these problems, this paper describes how to develop a high precision 3D laser scanning system, which enables scanning the cavity rapidly, obtaining the same resolution point cloud, calculating volume of the cavity, marking the deformation area correctly and providing visualized environment. At the same time, this device has realized remote control functionality to avoid people to work on the underground. The measurement accuracy of the 3D laser scanning system is +/- 2cm. The 3D laser scanning system can be combined with the mine microseism monitoring system to help with the estimation the cavity's stability and improve the effect of cavity monitoring.