The　Partially　Concrete　Filled　Steel　Tube　(PCFST)　structure　has　gradually　been　applied　to　bridges　as　the　main　load　carrying　components　in　recent　years,　owing　to　the　advantages　of　light　weight　and　high　stability.　The　failure　mechanism　and　load　carrying　capacity　of　PCFST　structure　highly　depends　on　the　concrete　filling　ratio.　For　this　purpose,　the　failure　mechanism　and　parametric　analysis　of　a　single　arched　PCFST　cable　stayed　bridge　tower　are　investigated　by　using　both　refined　solid　element　simulation　and　quasi-static　experiment.　The　results　shows　that　the　PCFST　arched　tower　experiences　asymmetrical　instability　failure　subjected　to　quarter　span　symmetrical　loading,　and　the　plastic　hinges　appears　firstly　at　the　tower　arch　closely　above　the　tower　columns,　and　then　the　bottom　of　the　tower　columns,　forming　a　rotating　mechanism　leading　to　the　instability　failure.　Filling　concrete　or　not　will　result　in　two　opposite　deforming　propagations　of　the　plastic　hinges,　and　when　the　concrete　filling　length　exceeds　the　length　of　plastic　hinge,　the　initial　rigidity　and　ultimate　load　carrying　capacity　of　the　PCFST　structure　will　sharply　increase.　Finally,　according　to　the　results　of　the　extended　parametric　analysis　based　on　the　real　size　simulation,　an　improved　initial　stress　reduction　coefficient　of　PCFST　structure　is　then　suggested.