In　order　to　study　the　calculation　method　of　stress　concentration　factor　(SCF)　for　concrete-filled　steel　tubular　KK　(CFST-KK)　joint,　model　tests　and　finite　element　(FE)　analysis　of　CFST-KK　joint　were　carried　out,　and　the　correctness　of　the　FE　model　was　verified　by　comparing　the　FE　results　to　the　test　results.　Based　on　the　parameter　analysis　of　FE,　the　sensitivity　of　SCF　of　CFST-KK　joint　and　the　influence　mechanism　of　concrete　in　steel　tube　were　revealed.　The　applicability　of　existing　calculation　methods　of　SCF　for　intersecting　tube　joint　were　discussed,　and　based　on　the　joint　stiffness　the　calculation　method　of　SCF　of　circular　hollow　section　KK　(CHS-KK)　joints　was　derived.　By　applying　the　principle　of　deformation　similarity　and　considering　the　peeling　deformation　between　inside　concrete　and　wall　of　main　tube,　the　calculation　method　of　SCF　of　CFST-KK　joints　was　proposed.　The　results　show　that:　the　maximum　error　of　FE　model　is　8.　0%,　implying　that　it　possesses　good　precision;　when　calculating　SCF　of　CFST-KK　joint,　it　is　allowed　to　only　consider　the　effects　of　axial　force　and　bending　moment　in　plane　with　the　effect　of　bending　moment　out　of　plane　ignored;　the　ratio　of　diameter　to　thickness　of　main　tube　has　the　most　significant　effect　on　SCF　of　CFST-KK　joint;　filling　concrete　in　main　tube　can　improve　the　radial　stiffness　of　main　tube　wall,　and　reduce　SCF　of　CFST-KK　joint　by　28.　5%　~　48.　9%;　when　applying　existing　calculation　method　of　SCF　of　intersecting　tube　joint　to　calculating　SCF　of　CFST-KK　joint,　there　are　still　large　errors;　based　on　the　parameter　analysis　of　extended　finite　element,　it　is　verified　that　the　proposed　calculation　methods　of　SCF　for　CHS-KK　and　CFST-KK　joints　possess　good　precisions,　and　the　calculated　results　are　more　conservative.　©　2025　Chinese　Society　of　Civil　Engineering.　All　rights　reserved.