Research conclusions: In this new composite foundation，the CFG piles bears the most loads of the soiling filling of subgrade，the MIP pile bears some loads of the soil filling of the subgrade and the soil between piles bears a little load of the soil filling of the subgrade． They bear the load together and it satisfy the bearing capacity of the subgrade and fit to the design concept of the composite foundation． This new composite structure can control the total settlement and uneven settlement while make the rapid completion of the foundation settlement to ensure that the post － construction settlement can meet the code requirement and the track stability of high － speed railway is good during the operation． The research result is of the great significance and reference to the design and construction soft soil foundation．