In　order　to　study　the　fatigue　performance　of　concrete-filled　steel　tubular-KK　(CFST-KK)　joint,　a　fatigue　test　on　CFST-KK　joint　models　was　conducted,　and　the　stress　distribution　pattern　and　fatigue　performance　evolution　of　CFST-KK　joints　were　analyzed.　A　solid　finite　element　(FE)　model　of　CFST-KK　joint　was　established.　In　combination　with　the　results　of　the　test　and　FE　models,　the　difference　in　the　fatigue　performance　between　the　CFST-KK　joint　and　the　concrete-filled　steel　tubular-K　(CFST-K)　joint　was　revealed,　the　influences　of　different　parameters　on　the　fatigue　performance　of　KK　joint　were　analyzed,　and　an　appropriate　fatigue　life　evaluation　method　for　the　CFST-KK　joint　was　discussed.　Research　results　show　that　the　maximum　hot　spot　stress　of　CFST-KK　joint　calculated　by　the　quadratic　extrapolation　method　is　located　15°　away　from　the　crown　point　on　the　chord　side　of　tension　brace　to　the　chord　intersecting　weld　towards　the　outer　saddle　point.　In　calculating　the　stress　concentration　factor　(SCF)　of　CFST-KK　joint,　the　nominal　stress　of　the　brace　only　takes　into　account　the　influence　of　axial　force　and　in-plane　bending　moment　regardless　of　the　impact　of　out-of-plane　bending　moment,　and　the　SCF　of　CFST-KK　joint　is　6.36,　80.2%　higher　than　that　of　CFST-K　joint.　The　fatigue　crack　in　the　CFST-K　joint　originates　at　the　location　with　the　highest　stress　concentration,　extends　towards　the　two　sides　and　wall　thickness　of　the　chord　along　the　weld　toe　root　during　repeated　loading,　and　expands　slightly　faster　towards　the　outer　saddle　point　than　the　inner　saddle　point.　However,　it　does　not　penetrate　the　chord　wall　after　stopping　the　repeated　loading.　The　fatigue　resistance　of　CFST-KK　joint　differs　significantly　from　that　of　CFST-K　joint,　primarily　due　to　the　presence　of　out-of-plane　bending　moment　in　the　brace　and　the　spatial　interaction　between　the　braces.　Filling　the　tube　with　concrete　can　enhance　the　radial　stiffness　of　CFST-KK　joint　and　reduce　the　stress　concentration.　Augmenting　the　angle　beyond　the　branch　face　can　enhance　the　spatial　interaction　between　the　braces.　Taking　into　account　the　impact　of　filled　concrete,　the　hot　spot　stress　and　fatigue　life　curve　of　CFST-K　joint　has　high　precision　in　assessing　the　fatigue　life　of　CFST-KK　joint.　©　2024　Chang＇an　University.　All　rights　reserved.