Square　ultrahigh-performance　concrete-filled　high-strength　steel　tubes　(S-UCFSTs)　exhibit　significant　potential　for　usc　in　long-span　bridges　and　super　high-rise　buildings.　To　investigate　the　axial　compressive　behavior　of　S-UCFST　short　columns,　tests　were　condueted　on　16　S-UCFST　short　columns.　The　effects　of　several　Parameters,　including　the　compressive　strength　of　concrete,　yield　stress　of　steel,　and　width-to-thickness　ratio　of　the　steel　tube,　on　axial　compressive　Performance　were　considered　in　this　study.　Nonlinear　finite　element　and　parametric　analyses　of　the　speeimens　were　condueted　using　ABAQUS　to　investigate　the　mechanism　of　the　S-UCFST　short　columns　under　axial　compression.　The　results　show　that　the　S-UCFST　short　columns　cxhibit　favorablc　axial　compressivc　bchavior.　Incrcasing　the　compressive　strength　of　concrete　improves　the　axial　compressive　strength　and　stiffness　but　minimally　affects　the　ductility.　The　axial　compressive　strength　is　improved　by　increasing　the　yield　stress　of　steel,　whereas　the　effects　of　stiffness　and　ductility　are　minor.　Reducing　the　width-to-thickness　ratio　of　the　steel　tube　improves　the　axial　compressive　strength,　stiffness,　and　ductility　while　delaying　the　oecurrence　of　local　buckling　and　shear　failure　in　S-UCFST　members.　Finally,　the　existing　statistics　and　experimental　results　were　compared　with　theoretical　results　calculated　aecording　to　Chinese　code　GB　50936—2014,　European　code　EC4　(2004),　and　American　code　AISC　360-22.　The　comparisons　indicatc　that　GB　50936—2014　presents　a　significant　prediction　bias　for　the　axial　compression　strength　of　S-UCFST　short　columns.　The　predictions　of　European　code　EC4　(2004)　are　not　sufficiently　safe　and　fail　to　aecount　for　the　local　buckling　of　the　steel　tube.　The　results　calculated　aecording　to　American　code　AISC　360-22　are　morc　similar　to　the　experimental　results　and　consider　the　local-buckling　effect　of　the　steel　tube.　©　2025　Chang＇an　University.　All　rights　reserved.