This study focused on the experimental evaluation of hollow sandwich composite members subjected to combined bending and torsion. The sandwich composite design is composed of dual steel tubes with concrete filled in-between. Steel tubes with various sectional dimensions were used to fabricate the specimens. A series of combined loading tests, including bending, torsion and their combination, on 14 composite members with various sectional compositions were conducted to investigate the relationship between the sections' compositions and the members' performance. It was found from the test results that the strength and energy dissipation of sandwich composite members with adequate sectional compositions were higher than those of concrete-filled tubes with similar dimensions. A simplified expression for member strength estimation under combined bending and torsion was proposed for engineering practice references.