Micro-seismic phenomena,occurring when rock masses are subjected to forces and failures,allow the determination of their unstable states and failure zones by analyzing micro-seismic signals.We first present the principles of micro-seismic monitoring and location,as well as an underground explosion-proof micro-seismic monitoring system.Given a practical engineering application,we describe the application of micro-seismic monitoring technology in determining the height of a "two-zone" overburden,i.e.,a caving zone and a fracture zone,the width of a coal-pillar section and the depth of failure of a floor.The workfaces monitored accomplished safe and highly efficient mining based on our micro-seismic monitoring results and provide direct proof of the reliability and validity of micro-seismic monitoring technology.