Abstract: Based on large scale model test system, cast-in-situ XCC pile-raft composite foundation embedded in sand is studied. Under the sine and "M" wave loads, the change laws of X pile-raft composite foundation are analyzed from aspects of cumulative settlement, dynamic displacement amplitude, dynamic stiffness and vibration velocity. The dynamic response of X pile-raft composite foundation is preliminarily revealed. The test results show that the settlement curve (s-N) of this composite foundation (s is the settlement and N is the load cycle) can be discribed by the logarithmic functions. The dynamic displacement amplitude and dynamic stiffness are related to the form of load and its amplitude. The vibration velocity gradually decreases with the increasing depth. The gravel cushion exerts a good damping effect on the soil in the process of broadcasting velocity to the soil foundation.The research results provide a reference for the use of pile-raft composite foundation.