The　use　of　a　self-compacting　lower　expansion　concrete　in　a　concrete-filled　steel　tube　(CFST)　structure　not　only　promotes　the　quality　of　concrete　pouring　but　also　improves　the　bond　behaviour　between　the　steel　and　the　concrete.　In　combination　with　the　actual　stress　state　of　the　columns　in　the　engineering　structure,　it　is　necessary　to　study　the　eccentric　compression　behaviour　of　the　column.　In　this　study,　experimental　studies　involving　both　uniaxial　and　biaxial　bending　tests　of　rectangular　self-compacting　lower　expansion　CFST　columns　were　carried　out.　The　variation　laws　of　the　load-displacement　curves,　the　lateral　deflection　curves　and　the　stress-strain　curves　during　the　loading　phase　were　analysed.　Furthermore,　the　failure　modes　and　the　mechanical　properties　of　the　specimens　under　eccentric　compression　loads　were　investigated.　Subsequently,　the　numerical　models　of　CFST　columns　with　self-compacting　lower　expansion　concrete　were　considered　and　established.　In　order　to　verify　the　rationality　of　the　finite　element　modelling,　the　numerical　calculation　results　were　compared　with　test　results.　Then,　a　parametric　analysis　of　the　compression　and　the　bending　bearing　capacities　of　each　column　was　carried　out　by　changing　the　eccentricity　of　the　load,　and　the　N-M　curves　or　N-M-x-M-y　surfaces　describing　the　ultimate　bearing　capacity　of　the　column　were　obtained.　Finally,　by　the　parametric　finite　element　analysis　of　the　rectangular　CFST　columns　regarding　to　the　bearing　capacity　under　the　same　eccentricity,　a　conclusion　was　obtained:　when　the　expansion　agent　content　gamma　of　a　specimen　increased　from　0%　to　10%,　the　bearing　capacity　of　the　columns　increases　significantly,　but　when　continue　increasing　the　expansive　agent　content,　the　expansion　agent　content　has　little　effect　on　the　compression-bending　bearing　capacity.