Abstract: The fill soil of different heights around buildings would easily lead to salty problems. In order to solve it and reduce the cost of pile foundation, the design philosophy for composite long-short pile foundation is presented when some bearing soil existing. Long piles are mainly build to control the settlement and short piles as well as soil mainly to provide bearing capacity. The 3D finite element method is used to simulate the performances of a short pile foundation and a composite long- short pile foundation by the fill soil. The results indicated that the composite long-short pile foundation can greatly cut the cost of pile foundation and effectively control the different settlements. So the composite long-short pile foundation may solve the salty problems and the design philosophy is useful.