A　prefabricated　L-section　thin　concrete　encased　steel　(L-TCES)　column,　which　could　be　prefabricated　in　shop,　connected　on　site,　and　not　convex　out　of　wall,　was　proposed.　Changing　the　proportion　of　steel　sectional　area,　concrete　strength,　stirrup　spacing　and　the　concrete　encasement　thickness　outside　the　flange,　experimental　and　numerical　investigations　were　conducted　on　the　axial　compression　performances　of　the　proposed　composite　column,　and　the　failure　modes,　load-displacement　curves,　load-strain　curves　and　characteristic　resistances　were　analyzed.　According　to　the　results,　the　concrete　encasements　and　reinforcements　can　restrain　the　steel　buckling,　and　increasing　the　proportion　of　steel　sectional　area　or　the　concrete　strength　can　improve　the　ultimate　resistance　and　stiffness　of　the　column.　Increasing　the　thickness　of　concrete　encasement　outside　the　flange　could　prevent　the　concrete　from　cracking,　and　compared　with　steel　column,　the　resistance　of　steel　in　the　composite　column　can　be　more　fully　utilized　under　the　ultimate　load.　The　formulas　to　calculate　the　design　and　ultimate　resistance　for　the　composite　column　with　closed　stirrup　were　proposed,　providing　results　with　satisfactory　accuracy.　The　simplified　model　of　load-displacement　curve　was　proposed　and　validated　against　the　test　results.