To　strengthen　the　composite　action　of　square　steel　tube　and　inside　concrete,　PBL　connectors　are　proposed　in　concrete-filled　square　steel　tubular　columns.　With　the　parameters　of　slenderness　ratio　and　eccentricity,　tests　on　the　mechanical　behavior　of　concrete-filled　square　steel　tubular　column　stiffened　with　PBL　under　eccentric　compressive　load　were　carried　out.　To　investigate　the　role　of　PBL,　the　contrast　tests　on　specimens　of　concrete-filled　square　steel　tubular　column　and　concrete-filled　square　steel　tubular　column　with　steel　plate　stiffener　were　also　carried　out.　Test　results　indicate　that　failure　modes　of　specimens　with　PBL　stiffener　and　steel　plate　stiffener　are　steel　tube　double　wave　buckling　at　compressive　side.　For　the　specimen　without　stiffener　is　single　wave　buckling　failure.　Ultimate　bearing　capacity　of　specimen　with　PBL　stiffener　is　6.95%　higher　than　specimen　without　stiffener,　and　is　4.33%　lower　than　specimen　with　steel　plate　stiffener.　PBL　stiffener　can　make　steel　tube　and　concrete　work　together　better.　The　concrete　crack　distribution　is　more　uniform,　and　the　width　and　spacing　of　concrete　crack　are　smaller.　Based　on　the　simplified　calculation　method　of　concrete-filled　square　steel　tubular　column,　considering　the　role　of　PBL　stiffener　and　concrete　tendon,　the　ultimate　bearing　capacity　formula　for　concrete-filled　square　steel　tubular　column　stiffened　with　PBL　subjected　to　eccentric　compressive　load　was　proposed,　which　can　provide　calculated　results　agreeing　well　with　the　experimental　results.　©　2017,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.