Based on lateral restraint effect of long pile, conducts a numerical simulation with the large FEM software ADINA on the properties of the composite foundation with tapered piles and cylindrical piles under the flexible foundation, obtains the average differential settlements of pile and soil and the pile-soil stress ratio under different magnitudes, and compares it with no lateral restraint. The results show that the working properties of the composite foundation with tapered piles are much better than that with the cylindrical piles under the condition of lateral restraint: the differential settlements between pile and soil are decreased and the pile-soil stress ratio are reduced, therefore improves the working properties of composite foundation. Provides beneficial references for engineering application. Keywords ：composite foundation；lateral constraints；wedge pile；flexible foundation；numerical simulation