Recycled　aggregate　concrete-filled　steel　tube　(RACFST)　columns　are　widely　used　in　engineering　practice　due　to　the　advantages　of　avoiding　steel　tubes　corrosion　and　reducing　self-weight　of　the　elements.　A　three-dimensional　solid　numerical　modeling　was　established　with　the　RACFST　columns　after　fire　as　the　object.　The　effect　of　steel　tube　wall　thickness　(steel　content)　and　concrete　material　type　was　analyzed　in　accordance　with　the　finite　element　model　(FEM).　A　comparison　of　the　FEM　specimens　with　the　experimental　specimens　was　analyzed.　It　was　found　that　the　FEM　results　were　close　to　the　experimental　results.　The　failure　modes　of　RACFST　columns　were　partial　buckling　of　the　steel　tube　outward　on　all　sides,　and　certain　lateral　deformation　was　observed.　The　ultimate　strength　of　the　columns　after　fire　increased　with　increasing　the　steel　tube　wall　thickness.　The　concrete　materials　type　had　little　effect　on　the　ultimate　strength　of　the　columns　after　fire.　The　temperature　field　within　the　RACFST　column　observed　a　temperature　platform,　which　was　kept　at　100-150　degrees　Celsius　from　the　temperature-time　curves.　©　2024　Copyright　held　by　the　owner/author(s).