This　paper　presents　an　experimental　investigation　on　concrete-filled　double-skin　circular　hollow　section　(CHS)　cross　joints　under　axial　compression.　A　total　of　twenty-two　right-angled　CHS　cross　joints　with　different　brace　to　chord　diameter　ratio　(β),　inner　tube　to　outer　tube　thickness　ratio　of　chord　(ω)　and　hollow　ratio　of　chord　(χ)　were　tested,　in　which　eighteen　concrete-filled　double-skin　CHS　cross　joints　were　studied　for　different　shapes　of　inner　tube　of　chord,　two　traditional　empty　CHS　cross　joints　and　two　traditional　concrete-filled　CHS　cross　joints　were　tested　for　comparison.　The　joint　strengths,　failure　modes,　load-deformation　curves　and　strain　distribution　curves　of　all　specimens　are　reported.　The　effects　of　brace　to　chord　diameter　ratio　(β),　inner　tube　to　outer　tube　thickness　ratio　of　chord　(ω),　hollow　ratio　of　chord　(χ),　shape　of　inner　tube　of　chord　and　concrete　strength　on　the　behaviour　of　concrete-filled　double-skin　CHS　cross　joints　under　axial　compression　were　evaluated.　It　is　shown　from　the　comparison　that　the　ultimate　load　and　initial　stiffness　of　CHS　cross　joints　are　significantly　enhanced　by　strengthening　the　chord　member　with　inner　tube　and　concrete　infill.　Furthermore,　the　ultimate　strengths　are　increased　with　the　increase　of　the　β　ratio,　whereas　the　ultimate　strengths　are　decreased　with　the　increase　of　the　χ　ratio　for　all　types　of　concrete-filled　double-skin　CHS　cross　joints.　On　the　other　hand,　the　ultimate　strengths　are　enhanced　with　the　increase　of　the　ω　ratio　and　concrete　strength　for　all　types　of　concrete-filled　double-skin　CHS　cross　joints,　but　the　enhancement　is　insignificant.　The　corresponding　finite　element　analysis　was　also　performed　and　calibrated　against　the　test　results.　The　design　equations　are　proposed　based　on　the　test　and　finite　element　analysis　results　for　concrete-filled　double-skin　CHS　cross　joints,　which　are　verified　to　be　more　accurate.　©　2018,　Korean　Society　of　Steel　Construction.