Abstract: On the basis of filed loading test results of compacted cement-soil pile composite foundation, the cooperation mechanismof piles, surrounding soil and cushionis analyzed under vertical load.Analyzing model is proposed by considering the distribution behavior of skinfriction between the pile andthe surroundings, and the method to calculate the stress ratio of piles to soil isintroduced by considering harmony working of piles, surrounding soil and cushion in composite foundation.The bearing behavior of compacted cement-soil pile composite foundationis analyzed by using the analytical method.The factors influencing the stress ratio of piles to soil, such as cushion modulus, soil modulus of piles end, rigid ratio of pile and soil, pile length, area displacement ratio, are discussed by calculating stress ratio of piles to soil.It is shown that cushion modulus withrespect to soil modulus of piles end has bigger influence on the stress ratio of piles to soil.It has a effective length in compacted cement-soil pile composite foundation, and the stress ratio of piles to soil increases by increasing pile length and rigid ratio of pile and soil at the same time.