In　order　to　study　the　mechanical　behavior　and　failure　mode　of　concrete-filled　steel　tubular　(CFST)　truss　arch　bridge,　a　test　of　CFST　truss　arch　structures　was　conducted.　The　results　indicate　that　the　straight　web　members　bear　very　huge　loads　that　induce　plastic　deformation,　and　the　truss　arch　has　a　preferable　integrity　before　ultimate　load,　but　more　straight　web　members　enter　into　plastic　status　with　the　increase　of　loads.　The　plastic　area　developes　along　arch　axial　direction,　which　induces　redistribution　of　internal　force.　However,　local　buckling　happens　eventually　at　ends　of　straight　web　members　from　arch　crown　to　quarter　spans　at　ultimate　load.　As　the　loading　further　increases,　the　carrying　capacity　decreases　and　diagonal　web　members　crack　at　ends,　which　leads　to　the　instability　failure.　Nevertheless,　the　chords　and　welding　joints　of　CFST　arch　rib　do　not　crack　during　the　loading　process,　and　the　areas　of　intersecting　junction　do　not　fail.　At　last,　the　comparison　of　mechanical　behavior　and　failure　mode　of　truss　arch,　truss　girder　and　laced　column　were　carried　out　based　on　the　test.　The　results　show　that　they　are　different　and　the　web　members　for　truss　arch　undergo　very　large　vertical　load,　thus　the　design　and　checking　of　web　members　of　CFST　struss　arch　is　necessary　in　practical　engineering.　©　2015,　Science　Press.　All　right　reserved.