Abstract: On account of the main feature of deepsoft soil region, it is an innovation on adopting cement mixing piles and CFG piles of different stiffness and length to deal with the ground treatment. Based on the Harbin-Dalian passenger dedicated railway, this paper have conduct parameter inversion in combination with the HardeningSoil constitutive model, while site test and numerical analysis have been adopted to study the loading character of this kind of composite foundation. The result shows that CFG piles undertake most load of the superstructure, while cement mixing piles take the task of improving the characters of plastic-like flow soil and keeping the integrity of the system. Moreover, the cement mixing piles improve the CFG capacity by weakening the negative friction and the total capacity of composite foundation has been enhanced in turn.