Abstract: The large-diameter ultra-long piles are commonly adopted for constructing ocean platform foundations. The pile-sliding phenomenon frequently takes place because of the great weight of both the piles and the hammer. Engineering experience shows that during the process of pile sliding the shaft friction represents a very small representative of soil resistance. So the prediction of the area of pile sliding depends on the end resistance of soft clay. The mechanism of pile sliding is discussed. Different methods for estimating the end resistance during pile sliding are compared associated with practical engineering. A procedure for calculating the soil resistance is put forward. It is used to predict the end resistance of piles during pile sliding in a project. The calculated results agree well with the observed data, indicating that the proposed method may be helpful to the pile foundation designers in ocean engineering.