Abstract: After many years exploration in Donghewan Iron Mine，complex mining status appears，such as lots of mined-out areas，long remained time，and big security risk. In order to make early-warning before the geo-stress disasters occur in the mined-out area to take necessary security measures and to prevent major disasters，the early warning and forecasting system was established. Based on the rock mechanics test and the finite element stability analysis on mined-out area，the regions that are prone to generate major disasters are analyzed and the necessary monitoring scope is determined. With the selection of the advanced STL-12-type acoustic emission monitoring system，a complete acoustic emission on-line real-time monitoring system for hazardous areas is built. According to the indoor acoustic emission testing and on-site vibration waveform measurement，the rock acoustic emission database and other vibration waveform database are established，and the acoustic emission characteristics during the destruction process of rocks are summarized. By waveform analysis，the variety rule of acoustic emission information at geostress activities of mined-out area is grasped，and a comprehensive early warning and forecasting system is made. The 2-year practice showed that the system could provide technical support for pre-warning of mined-out subsidence in Donghewan Iron Mine.

Key words: Acoustic emission, Mined-out area, Geostress hazard, Prediction