A　novel　concrete　encased　extended　I-shaped　steel　composite　(EI-CES)　column　with　less　reinforcement　for　prefabricated　structures　is　proposed.　Eight　EI-CES　stub　columns　with　one　covered　by　concrete　fireproof　board,　and　two　bare　extended　I-shaped　steel　stub　columns,　are　tested　under　axial　compression　loads.　The　effects　of　stirrup　spacing,　stirrup　form,　proportion　of　steel　sectional　area,　and　concrete　compressive　strength　on　the　axial　compressive　behaviour　of　composite　columns　are　studied　by　test　and　finite　element　analysis.　According　to　the　results,　the　concrete　cover　with　less　reinforcement　can　prevent　internal　steel　instability　under　axial　compression.　25　mm　thickness　of　concrete　cover　can　satisfy　the　load-carrying　capacity　and　serviceability　requirements　for　the　composite　column.　The　premature　spalling　of　concrete　cover　can　be　prevented　by　installing　fireproof　board,　reducing　stirrup　spacing,　and　using　closed　stirrups.　The　proportion　of　steel　sectional　area　in　composite　columns　increasing　from　7.5　%　to　9.6　%　has　no　effect　on　the　maximum　material　full-utilization　coefficient,　but　can　reduce　premature　concrete　cracks　and　improve　the　residual　strength　of　EI-CES　columns.　The　concrete　compressive　strength　in　composite　columns　decreasing　from　C50　to　C30　can　improve　the　maximum　material　full-utilization　coefficient　and　residual　strength.　The　composite　columns　have　excellent　post-peak　deformability.　A　formula　for　the　axial　resistance　of　EI-CES　columns　is　proposed　and　validated.