Abstract: A nonlinear mathematical model for load transfer of belled tension pile-soil interface is established. The capacity model of the belled tension pile end is modified by field tests. Based on the assumed transfer functions the interaction between the belled tension pile and the soils is abstracted as the first-order differential equation system problem constrained by the specified boundary conditions. The Runge-Kutta method is used to solve this system of equations to obtain the internal forces and deformation of the belled tension pile, in short, the proposed approach is a practical new idea for analyzing belled tension piles as a useful supplement to traditional methods. Due to taking into account the nonlinear interaction between the belled tension pile and the soils, the theoretical model agrees well with the real performance of soils. By comparing the results obtained from the method with the field tests, the feasibility of the proposed model for the analysis of the belled tension piles is proved.