To　study　the　seismic　behavior　of　composite-sectioned　high　strength　concrete　filled　steel　tubular　(CSCFT)　columns,　quasi-static　tests　on　six　specimens　were　conducted.　The　test　variables　included　the　axial　force　ratio,　wall　thickness　and　width-to-thickness　ratio　of　square　steel　tube,　confinement　index　of　circular　concrete　filled　steel　tube　(CFT).　Test　results　indicate　that　the　failure　mode　of　the　CSCFT　column　specimens　is　characterized　by　wall　buckling　of　square　steel　tube　and　crushing　of　partial　concrete　between　the　square　steel　tube　and　the　circular　steel　tube　within　a　height　of　300　mm　from　the　column　base.　The　lateral　force-displacement　hysteretic　loops　are　plump.　At　the　peak　lateral　force,　the　drift　ratio　of　one　specimen　is　a　little　bit　less　than　1/100　since　it　has　a　design　value　of　axial　force　ratio　close　to　1.0,　and　the　drift　ratios　of　other　5　specimens　are　larger　than　1/100.　As　the　wall　width-to-thickness　ratio　of　square　steel　tube　reduced,　or　the　confinement　index　of　CFT　increased,　the　initial　secant　stiffness　and　the　ultimate　drift　ratio　are　increased.　As　the　wall　thickness　of　square　steel　tube　increased,　the　bending　strength　of　specimen　under　axial　compressive　force　is　enhanced.　The　bending　strength　of　the　specimens　calculated　by　the　superposition　method　and　by　the　plane　section　assumption　has　good　agreement　with　the　test　results.