Concrete　filled　double-skin　tubular　structures（CFDST）that　reuse　waste　steel　slag　demonstrate　advantages　in　sustainable　resource　use.　The　interaction　and　coordination　between　steel　tube　and　concrete　make　CFDST　an　effective　solution　to　the　stability　issues，considering　the　expansion　characteristic　of　steel　slag.　The　expansion　performance　of　the　steel　slag　concrete　can　enhance　the　bond　between　the　steel　tube　and　its　sandwich　concrete.　This　paper　presents　a　series　of　tests　on　a　steel　slag　CFDST　T-Joint　under　pseudo-static　loading　conditions　to　investigate　its　seismic　performance.　Five　specimens　were　tested，including　one　ordinary　concrete　test　specimen　and　four　steel　slag　concrete　test　specimens.　The　variables　tested　were　concrete　type，hollow　ratio，diameter　ratio，and　axial　compression　ratio.　The　results　show　that　while　the　bearing　capacity　of　steel　slag　concrete　specimens　is　slightly　lower　than　that　of　ordinary　concrete，the　displacement　ductility　and　energy　dissipation　capacity　significantly　increased，by　69.46%　and　48.20%　respectively.　As　the　hollow　ratio　increases　from　0.3　to　0.5，the　displacement　ductility　coefficient　of　the　specimen　increases　by　9.69%.　When　the　diameter　ratio　of　branch　main　increases　from　0.40　to　0.68，the　displacement　ductility　coefficient　increases　by　82.44%.　However，when　the　axial　compression　ratio　increases　from　0.1　to　0.2，the　displacement　ductility　coefficient　of　the　specimen　decreases　by　17.98%.　A　finite　element　model　was　established　to　simulate　the　hysteretic　properties　of　the　specimen.　The　simulation　results　are　in　agreement　with　the　test　results，verifying　the　validity　of　the　finite　element　model.　Based　on　the　verified　finite　model，the　parameters　of　influencing　factors　on　the　bearing　capacity　of　the　specimen　were　analyzed，and　the　optimum　hollow　ratio　of　the　specimen　was　found　to　be　about　70%.　The　use　of　steel　slag　greatly　improves　the　seismic　performance　of　the　CFDST　T-joint　and　can　be　widely　used　in　concrete-filled　steel　tube　engineering　structures.　©　2024　Nanjing　University　of　Aeronautics　an　Astronautics.　All　rights　reserved.