The　I-section　concrete　filled　steel　tube　(CFST)　column　and　the　bottom　strengthened　I-shaped　cross　section　CFST　column,　in　which　the　column　flange　was　welded　with　steel　plates,　were　proposed.　Three　column　models　with　different　constructions　were　tested　under　horizontal　low　cyclic　loading.　Model　1　was　a　conventional　I-section　CFST　column　;model　2　was　an　I-section　CFST　column　with　its　outer　part　at　the　bottom　of　flange　welded　with　steel　plates;　model　3　was　an　I-section　CFST　column　with　its　surrounding　part　at　the　bottom　of　flange　welded　with　steel　plates.　The　failure　characteristics,load-bearing　capacity,　stiffness　and　degradation　process,　ductility　and　hysteretic　energy　dissipation　capacity　of　the　models　were　analyzed.　The　calculation　formula　for　cross　section　and　oblique　section　load-bearing　capacity　of　bottom　strengthened　I-shaped　cross　section　CFST　column　was　given,and　the　results　obtained　from　the　calculation　are　in　good　agreement　with　those　from　the　experiments.　The　study　shows　that　the　load-bearing　capacity,　ductility　and　seismic　energy　dissipation　capacity　of　the　bottom　strengthened　I-section　CFST　column　are　improved　obviously　compared　with　the　conventional　I-section　CFST　column.