With the rapid development of high-speed railway in soft foundation, foundation treatment technology has become mature, the most outstanding is CFG pile composite foundation technique. CFG pile composite foundation is made of cement fly ash gravel pile(CFG pile), pile of soil and sandstone , between sand and gravel several problems such as the medium material composition together constitute layer. It has high bearing of capacity, convenient, low costing, strong adaptability and quality control easier.So it is widely applied and promoted. Under static and dynamic loads, the relations of the high-speed railway CFG pile composite foundation is very complex. In order to further understand the intensity of pile-net structure subgrade stability and deformation, pile , requirements of the high-speed railway roadbed ,it needs to do pile-net structure parameter sensitivity analysis. According to high-speed railway CFG pile composite foundation , the numerical analysis can well solve the coupling effect of piles and soil. So, this paper adopts FLAC3D finite difference software is simulated and analyzed.