Abstract: This paper is focused on the prestress-high-concrete(PHC) pipe-pile with the ratio of length to diameter over sixty in soft foundation area. According to the grey system theory, the load-displacement GM(1, 1) model for PHC single pile and the corresponding criterion for accuracy and bearing capacity check were set up.Then the prediction for PHC single pile ultimate bearing capacity was carried out by the limited measured data of a engineering project piles.The results show that for the PHC pipe-pile with the ratio of length to diameter over sixty in soft foundation area, regardless of the load-displacement curve(Q - s curve) is varied gradually or rapidly, the model is of high accuracy of prediction and the prediction meets the requirement of engineering.