In　order　to　assess　residual　bearing　capacity　of　concrete　filled　steel　tubular　(CFST)　members　after　high　temperature　subjected　to　biaxial　force　and　bending,　their　behaviors　were　analyzed　from　numerical　simulation,　experimental　study　and　theory　analysis　in　this　paper.　Numerical　analytical　procedure　was　verified　by　experiment　results　of　16　CFST　specimens　subjected　to　biaxial　eccentric　compression.　Damage　coefficient　of　bearing　capacity　(kr)　was　defined　and　the　main　factors　of　influencing　kr　were　analyzed.　The　representation　of　kr　was　obtained　by　regressed　analysis.　Combined　the　theoretical　analysis　with　formula　at　ambient　temperature,　a　simplified　formula　was　obtained,　which　could　analyze　the　bearing　capacity　for　rectangular　CFST　members　after　high　temperature　subjected　to　biaxial　force　and　bending.　Finally,　a　comparison　was　made　among　the　simplified　formula,　experimental　results　and　numerical　analysis,　and　the　results　show　that　they　are　in　a　good　agreement.　This　implies　that　the　proposed　simplified　formula　is　efficient　and　it　provides　a　technical　foundation　for　assessment　residual　behavior　and　retrofitting　of　post　fire　CFST　members.