High-strength　steel　columns　are　commonly　connected　by　welding.　However,　the　construction　environment　and　quality　of　construction　workers　have　a　large　impact　on　welding　quality,　especially　on　a　construction　site.　This　paper　investigates　the　mechanical　behavior　of　bolted　built-up　steel　column,　which　is　built　using　bolts　instead　of　welds.　Six　bolted　built-up　steel　columns　were　made　using　high-strength　steel,　referred　as　to　H-SA700,　and　tested　under　axial　loading　to　investigate　the　bearing　capacity　and　buckling　deformation.　The　main　experimental　parameter　was　the　slenderness　ratio.　In　addition,　finite　element　models　were　established　on　the　same　scale　as　the　tested　specimens,　and　a　supplementary　parametric　analysis　on　the　effects　of　intervening　plate　thickness,　intervening　plate　width,　angle　section　side　length,　and　bolt　pitch　on　the　bearing　capacity　of　specimens　was　conducted.　Moreover,　the　experimental　and　numerical　results　were　compared　with　the　calculated　ultimate　strength　obtained　from　the　corresponding　codes　of　GB　50017-2017,　ANSI/AISC　360-10,　EN　1993-1-1,　and　AIJ-2002.　The　results　showed　that　both　slenderness　ratio　and　angle　section　side　length　were　the　main　factors　on　the　bearing　capacity.　Japanese　code　gave　the　best　predictions　for　the　ultimate　load　of　bolted　built-up　steel　columns.