Abstract: Based on 1:5 scale track-subgrade-pile-raft composite foundation model, the dynamic response of ballastless track X-section cast-in-situ concrete (XCC) pile-raft composite foundation embedded in sand under sine wave loads (which can approximately simulate a train axle load) with different frequencies is investigated. This involves the measurement and analysis of response in velocity and dynamic soil pressure under different load frequencies. It is shown that, in the direction of cross-section of embankment, the velocity response mainly focuses on track-subgrade. The dynamic soil pressure of roadbed is "W"-shaped distribution and the dynamic soil pressure of subsoil surface is "U"-shaped distribution in the direction of cross-section of embankment. The dynamic load magnification factor of roadbed increases with the increasing load frequency. The research results may provide an insight into the theoretical analysis and calculation of ballastless track XCC pile-raft composite foundation, and validating its dynamic load magnification factor.