The　existing　concrete　structure　design　is　based　on　the　study　of　small-size　components.　As　a　result　of　the　size　effect　of　concrete　structures,　whether　it　is　scientific　and　rational　to　design　large-size　component　of　that　type　should　be　further　studied.　The　experiment　on　size　effect　of　the　reinforced　concrete　column　under　axial　loading　was　carried　out　in　the　multifunction　press　with　ultimate　load　of　40000kN.　Specimens　were　designed　in　accordance　with　the　relevant　similarity,　whose　geometric　dimensions　are:　200mm　×　200mm　×　900mm,　400mm　×　400mm　×　1800mm　and　600mm　×　600mm　×　2700mm.　Based　on　the　result　of　the　experiment,　the　failure　characteristics,　ultimate　strength　and　stress-strain　curves　of　various　specimens　were　comparatively　analyzed.　The　results　show　that,　within　a　certain　size　range,　with　the　geometric　size　increasing,　the　carrying　capacity　of　the　reinforced　concrete　column　calculated　in　the　standard　formula　from　the　current　code　is　closer　to　the　corresponding　carrying　capacity　experimental　value,　which　reduces　the　reliability　of　the　formula;　the　peak　strain　of　reinforced　concrete　columns　under　axial　loading　reduces　with　the　geometric　size　increasing.