This　paper　attempts　to　investigate　the　effect　of　various　parameters　on　the　axial　compressive　behavior　of　nano-silica　concrete-filled　angle　steel　reinforced　GFRP　tubular　columns.　The　proposed　new　composite　column　consists　of　three　parts:　the　outer　GFRP　tube,　the　inner　angle　section　steel　and　the　nano-silica　concrete　filled　between　GFRP　tube　and　angle　section　steel.　Twenty-seven　specimens　with　different　nano-silica　concrete　compressive　strength　(20MPa,　30MPa　and　40MPa),　diameter-to-thickness　ratio　of　GFRP　tube　(20,　25　and　40)　and　steel　ratio　(0.008,　0.022　and　0.034)　were　tested　under　axial　load.　The　main　purpose　of　this　study　is　to　examine　the　effect　of　the　three　parameters　on　the　following:　failure　modes,　deformation　capacity,　load　bearing　capacity,　ductility　and　initial　stiffness　of　the　new　composite　column　under　axial　load.　It　was　found　that　the　load　bearing　capacity　and　initial　stiffness　increased　as　the　nano-silica　concrete　compressive　strength　of　the　specimens　increased.　But　the　specimens　with　higher　nano-silica　concrete　compressive　strength　showed　lower　deformation　capacity　than　that　of　the　specimens　with　lower　nano-silica　concrete　compressive　strength.　The　varieties　of　the　steel　ratio　have　no　significant　effect　on　the　specimens＇　axial　deformation　behavior.　Experimental　results　also　showed　that　both　load　bearing　capacity　and　deformation　capacity　increased　with　the　decrease　of　diameter-to-thickness　ratio　of　GFRP　tube.　However,　diameter-to-thickness　ratio　of　GFRP　tube　has　no　significant　effect　on　the　initial　stiffness　of　specimens.　The　confinement　coefficient　was　proposed　to　better　evaluate　the　confinement　effect　of　GFRP　tube　on　the　inner　angle　section　steel　reinforced　core　nano-silica　concrete.　The　confinement　effect　of　GFRP　tube　on　lower　strength　concrete　was　better,　and　the　confinement　effect　reduced　as　the　diameter-to-thickness　ratio　of　GFRP　tube　increased.　The　design　formulas　for　the　load　bearing　capacity　of　the　nano-silica　concrete-filled　angle　steel　reinforced　GFRP　tubular　columns　under　axial　load　were　proposed.　©　2019　K.　He　et　al.,　published　by　De　Gruyter　2019.