The ultimate shaft resistance of uplift pile is divided into two parts, one is the setting strength of pile and soil , which is irrelevant to the earth pressure of pile, and the other is the force of friction , which is proportional to the earth pressure of pile and can be calculated using the friction law. With assumption of elastic soil, this paper studies the pile-soil interaction through the integral calculation using Mindlin formulation. Pile-soil interface displacement coordinate equation is derived based on the solution of cavity expansion in infinite soil. Then a limit state equation of uplift piles and its solution are presented. The methods for determining the parameters of soil and pile are also given. The equation can be used to calculate ultimate bearing capacity of uplift piles with considering the influence of such factors as pile and soil materials, pile length, pile diameter, depth of pile top, group piles effects, unloading effect due to excavation, and so on. As an example, a full-scale test was performed on a large steel pipe pile with a length of 81.3m, a diameter of 1.7 m and a wall thickness of 25mm. The calculated and measured ultimate uplift bearing capacities are compared, showing that the proposed method for calculating the bearing capacity of uplift piles is satisfactory and applicable and has an accuracy much better than the methods recommended in the current codes of China.