Taking　the　pentagonal　multi-cavity　concrete　filled　steel　tubular　(　CFST　)　mega-columns　of　Dalian　International　Trade　Center　building　as　the　prototype,　eccentric　compression　performance　tests　of　two　mega-column　models　with　different　cross-section　constructions　were　carried　out　in　order　to　investigate　the　influence　of　cross-section　construction　on　eccentric　compression　behavior.　Specimen　CF-I　was　a　CFST　mega-column　model　with　pentagonal　quadruple-caved　section　without　reinforcement　cage　inside　and　Specimen　CF-II　was　that　with　reinforcement　cages　inside.　The　load-bearing　capacity,　load-deformation　curves　and　failure　characteristics　of　two　models　were　obtained　and　the　finite　element　simulation　was　carried　out　based　on　ABAQUS　as　well.　The　results　of　simulations　accord　well　with　the　test.　In　view　of　this,　simulations　are　carried　out　for　analyzing　the　effects　of　the　thickness　of　the　external　steel　tubular　plates,　the　separator　located　in　the　axis　of　asymmetry　and　peripheral　vertical　ribs　on　eccentric　behaviors　of　columns.　The　conclusions　are　drawn　that　the　additional　reinforcement　cages　can　improve　load-bearing　capacity　and　ductility,　the　increased　proportion　of　bearing　capacity　and　ductility　due　to　the　increase　of　thickness　of　external　plates　is　greater　than　that　due　to　the　increase　of　thickness　of　separator　located　in　the　axis　of　asymmetry,　and　that　the　damage　of　specimens　are　reduced　by　increasing　the　thickness　of　surrounding　vertical　ribs.