Forty-eight　circular　concrete-filled　steel　tube　(CFST)　columns　subjected　to　lateral　impact　were　tested　to　investigate　the　behavior　of　circular　CFST　columns　under　axial　compressive　load.　Analyses　of　effects　of　concrete　compressive　strength,　impact　location　and　impact　energy　on　residual　ultimate　axial　capacity,　ductility　and　initial　stiffness　are　provided　in　this　paper.　It　is　found　that　lateral　impact　has　negative　effects　on　residual　ultimate　axial　capacity　of　circular　CFST　columns　from　test　results.　Residual　ultimate　axial　capacity　decreases　as　impact　energy　increases　and　impact　location　comes　close　to　the　end　of　the　specimen.　It　is　also　found　that　increasing　concrete　compressive　strength　can　reduce　the　negative　effects　of　impact　location　on　residual　ultimate　axial　capacity.　Ductility　and　the　initial　stiffness　of　circular　CFST　columns　decrease　as　impact　energy　increases.　Ductility　and　the　initial　stiffness　increase　as　impact　location　varies　from　middle-length　to　the　end　of　specimens.　When　impact　energy　and　impact　location　are　constant,　the　ductility　of　the　specimen　with　30　MPa　of　concrete　compressive　strength　is　better　than　that　of　other　specimens　with　different　compressive　strength.　Besides,　analyses　of　strain　developments　for　12　typical　specimens　to　investigate　failure　modes　under　axial　compressive　load　are　provided　in　this　paper.　Strain　developments　have　indicated　that　the　steel　at　impact　location　becomes　plastic　faster　than　that　at　other　locations.　Based　on　the　test　results,　a　calculation　formula　is　presented　to　predict　the　residual　ultimate　axial　capacities　of　circular　CFST　columns　subjected　to　lateral　impact,　and　good　agreement　with　experimental　results　has　been　achieved.　©　2019　by　the　authors.