Based on the large-scale model test on the XCC pile-net composite foundation subjected to dynamic loading induced by high-speed train，the distribution characteristics of vibration velocity，dynamic stress，and dynamic displacement of foundation soil are analyzed under different train speeds. The vibration response of the track-subgrade system and attenuation law of dynamic stress of foundation soil under cyclic loading are discussed. A numerical model is established in this paper using PLAXIS 3D to study the effect of axle weight and vibration frequency of train on the vibration response of the composite foundation. Moreover，the vertical stress distributions of pile top soil and soil between piles under dynamic loading are compared between non-reinforced embankment and double-layered geogrid reinforced embankment. The results show that the vertical displacement of the track slab changes periodically with the time of“M”type；the vertical velocity is the largest at the surface of the embankment，and gradually attenuates along the horizontal and depth direction of the foundation. The vertical velocity attenuates nearly 90% in the embankment. With the increase of loading frequency and loading amplitude，the vibration velocity of soil increases gradually. The dynamic loading has a significant effect on the unreinforced embankment，which weakens the soil arching effect. The vertical stress ratio of pile to soil decreases with the increase of loading frequency. Additionally，the tension membrane effect of geogrid reinforced embankment can reduce the influence of dynamic loading on composite foundation.