Abstract: The deflection of concrete filled steel tubular columns subjected to lateral impact load are studied. Three influence factors including impact energy, casing hoop steel coefficient and restrained ends type are measured in dropped hammer impact test. Furthermore, the relationships between final mid-span deflection and the three factors are found out and discussed respectively. Failure states are recorded. The final mid-span deflection and deflection curves are also simulated by using ANSYS/LS-DYNA. The results from numerical simulation agree well with experimental results.