Abstract: Based on some simplifications, the embankment, improved area and substratum are treated as a whole with continuous displacements and stresses. A settlement calculation model for the improved area of the composite foundation under embankment load is developed, especially taking the penetration of the pile top, the interaction between column and surrounding soil, and the penetration of the pile end into account. And a finite difference method is presented to solve the calculation model. Based on 3D numerical simulation results, a simplified method is used to calculate additional stresses in substratum of the composite foundation under embankment load, with the stress concentration phenomenon taken into consideration. Then the settlement calculation method of the composite foundation under embankment load is presented. The computational results indicate that the settlement calculated with composite modulus method is smaller while that with a modified stress method is far lager than observed data, and the result calculated with the proposed methods agrees well with observed data.