Abstract: It is important for engineers to determine the ultimate bearing capacity of single piles through non-destructive field test. Based on field test data of initial loading, GM(1,1) prediction model can be established to determine the bearing capacity of piles. This method has been proved to be effective in engineering practices. However, the prediction accuracy should be improved. In this paper, some concepts and principles of buffer operators are presented systematically and their application in practice is illustrated. Then buffer operator is used to modify GM(1,1) model to predict the bearing capacity of piles. Its accuracy is verified by engineering examples. The new model could be applied in engineering practices and theoretical studies.