A single-point GM (1,1) model was expanded into a multi-point mode1 with consideration of the correlation and interaction between multiple points. The self-adaptive MGM (1,n) model, was used for modeling and prediction of multi-point deformation, coded in Matlab. The model was applied to the prediction of deformation of the Wangxia Rock, which is an unstable rock. The results show that the predicted values agreed with the measured values, and the model had better effects, higher precision, and more accurate results than the traditional GM (1,1)model in predicting the deformation of unstable rocks.