Concrete-filled double skin tubes (CFDST) have a great potential to be applied in the construction of high-rise buildings and bridge piers. In practice, columns often bear additional torque when earthquake occur. This paper describes a series of torsion-bending combined loading tests carried out on CFDST, both outer and inner are circular hollow section. Purpose of this study is to investigate their seismic performance experimentally. The two test parameters of this research considered were a sectional void ratio and an eccentric ratio of loading. As a result, CFDST members were found to have significant increase in strength, stiffness, ductility and energy absorption compared with the same dimension circular concrete-filled tubular members, it also showed that the energy absorption capacities decreased when sectional void ratio increased, and further verified from response comparisons that the members’ stiffness deterioration rates were increased when sectional void ratio increased. The purposed methods for ultimate strength predictions of composite members were in good agreement with the experimental results. Finally, a simplified expression for composite members’ stiffness evaluation was proposed for engineering references.