Based on the successful use of the multi-channel acoustic emission(AE) system in forecasting a roof caving of mined-out area in a mine,the characteristic parameter of the AE events occurring in the roof caving of mined-out area within the range of a week was statistically analyzed,the monitored AE signal was classified.The waveform changes of AE in rock mass under different stress was presented,the portentous AE laws of rock mass failure was summarized.These have a better reference value to the application of AE in the monitoring of similarly mining and geotechnical engineering.