Abstract: Considering that the traditional acoustic emission parameter analysis which was based on short-term parameters prediction was easily disturbed by external environment and the AE parameters were used imperfect,the paper introduced the acoustic emission cumulative difference indicator which took into account of acoustic emission fluctuation during aperiod of time,so the indicator can weaken the interference factors,and it can predict the goaf instability more accurately.By applying the Acoustic Emission Cumulative Difference Indicator predicted the goaf instability of 104^# ore body in Fozi mine,the prediction result was consistent with the reality.