Abstract:The conventional GM(1,1) model is highly limited and prone to accumulate systematic error in prediction. The paper traces its error sources and proposes an improved method. This improved model is applied for analyzing the monitoring data from eight successive years of a high rock slope monitoring of the Bikou hydroelectric power station,where the sixth and the seventh years’ data is omitted. A grey safety monitoring model of the high rock slope is established by using the improved GM(1,1) prediction model. By comparing the prediction results of the improved GM(1,1) model with those of the conventional GM(1,1) model and the statistical model,and with those of the mean error,correlation coefficient,and maximum error,it is proved that the modified GM(1,1) model is of high accuracy in safety monitoring and its prediction agrees well with the actual behavior of the high rock slope.