To　investigate　the　influence　of　longitudinal　reinforcement　strength　grade,　stirrup　spacing,　concrete　strength　and　axial　load　ratio　(ALR)　on　seismic　behavior　of　high-strength　concrete　(HSC)　columns,　seven　full-scale　square　HSC　columns　reinforced　with　high-strength　steel　bars　(HSSB)　with　nominal　yield　strength　of　600　MPa　or　conventional　steel　bars　were　tested　under　constant　axial　load　and　cyclic　lateral　load.　Furthermore,　corresponding　nonlinear　finite　element　analysis　was　conducted　in　ABAQUS.　The　column　top　deformation　and　lateral　load　at　different　service　states,　stiffness　degradation,　bearing　capacity　degradation　and　strain　of　longitudinal　and　transverse　reinforcement　were　discussed.　The　test　result　shows　that　using　steel　bars　with　nominal　yield　strength　of　400　MPa　as　stirrup　is　a　better　choice　for　HSC　columns　and　ALR　is　an　important　factor　which　determines　whether　the　high-strength　longitudinal　reinforcement　can　reach　its　compressive　or　tensile　yield　strain　before　maximum　point.　Taking　HSSB　as　longitudinal　reinforcement　(equivalent　volume　replacement)　greatly　improves　the　seismic　behavior　of　HSC　columns.　After　taking　the　influence　of　strain　gradient　on　stress-strain　relationship　of　compressive　concrete　into　consideration,　a　confined　strain　gradient　model　(CSGM)　which　was　suitable　for　finite　element　analysis　(FEA)　was　established　based　on　the　model　established　by　Razvi　and　Saatcioglu.　Specific　verification　of　finite　element　model　(FEM)　on　deformation　and　lateral　load　at　different　service　states　were　presented　for　further　parameter　analysis.　The　trend　of　displacement　ductility　factor　were　investigated　in　detail　in　numerical　analysis　part.　With　proper　ALR　and　stirrup　characteristic　value,　HSC　columns　reinforced　with　HSSB　is　able　to　present　a　displacement　ductility　of　higher　than　4,　which　is　capable　to　meet　the　ductility　demand　of　most　codes.