Abstract: The mechanism of the relationship between the ultimate bearing capacity and the terminative jacking force is studied from two aspects of pile installation process and time-effect, in which the concept of friction fatigue coefficient and time-effect coefficient is demonstrated. The ultimate bearing capacity is predicted based on Q-S curve according to the grey theory, and the results are closely related to the final settlement of static load tests. The data of about 2000 jacked concrete piles are studied. It is found that the ratio between the ultimate bearing capacity and the terminative jacking force increases with the ratio between the pile length and the diameter hyperbolically, and is confirmed as F probability distribution. The expressions under different geological conditions are derived by regression analysis. The ratio between the ultimate bearing capacity and the terminative jacking force increases more rapidly when the bearing stratum is cohesive soils than others, and this ratio of the pile in silt is usually larger than that in other soils with the same bearing layer and shape. The ultimate bearing capacity will be smaller than the terminative jacking force of jacked piles with small length, which attributes to the resilience and stress release of the soils around pile tip after construction.