Abstract: Abstract: In order to obtain rock acoustic emission time-energy parameters, uniaxial whole process loading experiment is used on rock sample based on the rock acoustic emission technology. Energy judging index K_SN is put forward to predict the failure time of rock sample. According to the experimental results, MATLAB is used to draw acoustic emission energy fitting line y_SN and the energy judging index K_SN is calculated. The results show that，with the load of rock sample, the trend of energy judging index K_SN is decreased compared with the previous period. As the lapse of time, the trend becomes more and more obvious. When the trend of energy judging index K_SN increased, the rebound phenomenon of energy fitting line y_SN appears. It foreshows that the failure of rock sample is coming soon. Analysis method of energy judging index K_SN can also be used to forecast earthquake and mine earthquake.