Strength composite pile is a new type of pile formed by inserting a precast concrete pipe pile into soil-cement column. A series of shaking table model tests and finite difference analysis using FLAC3D were carried out to examine the seismic response of strength composite pile in a liquefiable ground. The accuracy and reliability of the numerical model were verified by the model testing results, and the effect law of diameter, length and modulus of soil-cement columns on the seismic response of sand-composite pile-superstructure were clarified. In addition, the anti-liquefaction performance of liquefiable ground and the bending failure of composite piles were evaluated. Results show that increasing the diameter and length of soil-cement column can effectively improve the seismic performance of composite pile. Increasing the shear modulus of soil-cement column to improve the seismic performance of composite piles is limited. A large moment response may occur in the pile near pile head or at the interface of cement-improved soil and liquefiable sand, so necessary seismic structural measures should be considered at the part. Based on the evaluation results, the key points of seismic design for composite piles in liquefiable soil were proposed.