Abstract: On the basis of field tests on carbinol storage tank foundation, investigations are conducted on the bearing capacity and pile-soil load share ratio of rigid pile composite foundation with different rigidities. Studies show that change of the foundation rigidity has significant effect on the development of pile-soil bearing capacity and load share ratio. Under the same cushion thickness, pile length and space, the bearing capacity of pile and soil can both develop sufficiently for the foundation with enough rigidity. While for the flexible foundation, the bearing capacity of soil between the piles can develop sufficiently, but that of the piles develops little. The pile load share ratio of rigid pile composite foundation is larger than that of flexible foundation. But the soil load share ratio of flexible foundation is larger than that of rigid foundation