Abstract: The composite foundation with concrete core sand-gravel piles has the advantages of high bearing capacity of the rigid pile composite foundation and fast drainage consolidation of sand well foundation. It is necessary to consider, in the calculation of the composite foundation consolidation, the unique load transfer among the rigid pile, sand pile and soil body, and the circular drainage channel. Considering the annular drainage section of sand-gravel columns composite foundation, using the initial condition of loads beared by soil and pile, the control equation and the analytical solutions for the composite foundation are obtained, and the average degree of consolidation is given by calculation. Finally the comparisons between the calculated results and the field measured data show that the calculated excess pore water pressure, the degree of consolidation and the settlement-time relationships are well consistent with those of the field data, by which the calculation method has been verified.