Geopolymer　concrete　(GC)　is　green　and　environmentally　friendly.　In　order　to　comprehensively　study　the　mechanical　properties　and　influence　mechanism　of　geopolymer　concrete-filled　steel　tubular　(GCFST)　columns　under　various　working　conditions,　this　study　takes　the　strength　grade　of　geopolymer　concrete,　length-diameter　ratio　and　wall　thickness　of　steel　tube　as　design　parameters.　Eight　GCFST　columns　are　designed　and　the　compressive　performances　are　conducted　under　repeated　axial　compression.　The　load–displacement　curve,　the　skeleton　curve,　the　characteristic　load　and　displacement,　the　ductility,　and　the　energy　dissipation　were　analyzed.　Furthermore,　the　numerical　analysis　models　were　established　through　finite　element　software　and　the　test　results　were　compared　with　the　simulation　results　to　verify　the　accuracy　of　the　finite　element　model.　The　results　indicate　that　under　different　length-diameter　ratios,　the　variation　trends　of　the　load–displacement　curves　for　the　specimens　are　slightly　different,　while　the　stiffness　degradation　curves　present　similar　variation　laws.　The　design　parameters　have　significant　effects　on　the　bearing　capacity,　average　compressive　force,　and　energy　dissipating　capacity　of　the　specimens.　The　simulation　results　are　in　good　agreement　with　the　experimental　results.　Research　results　show　the　excellent　bearing　capacity　of　GCFST　columns　and　the　precision　of　finite　element　calculation　results,　which　can　provide　a　reference　for　related　experimental　research.　©　The　Author(s)　2025.