Based on field testing data of 8 large-diameter super-length piles, this paper selected grey model GM(2,1) to predict pile bearing capacity, and carried out a comparison with two types of common exponential models. It was found that the relative error of the predicted value of pile bearing capacity was about±0.8% for 8 large-diameter super-length piles, and the validating effect was very good with the index p and index c; GM(2,1) was better than two types of common exponential models. It is concluded that GM(2,1) is a good model which doesn t limit sample number and can add new sample to assure higher-precision prediction; it is feasible to predict bearing capacity of large- diameter super-length pile based on GM(2,1).