A　fluid-structure　interaction　numerical　simulation　technique　based　on　CFD　has　been　developed　to　study　the　vortex-induced　vibration　behavior　of　steel　arch　bridge　hanger.　Above　all,　wind　acting　on　bridge　hanger　is　simulated　by　using　Flunet　and　then　vortex-induced　dynamic　motion　of　hanger　is　solved　by　Newmark-beta　method　in　the　User　Defined　Function　(UDF).　Finally　hanger＇s　transient　vibration　in　wind　is　achieved　by　dynamic　mesh　method　provided　by　Fluent.　Using　this　technique,　the　vortex-induced　vibration　behavior　of　hanger　of　the　Nanjing　Dashengguan　Yangtze　River　Bridge　is　analyzed,　including　vibration　amplitude,　vibration-started　wind　speed　and　vortex　shedding　frequency.　The　study　also　considers　influences　of　different　section　type　(rectangle,　chamfered　rectangle　and　H)　of　hanger.　The　following　conclusions　are　obtained.　Firstly　hanger　of　different　section　has　different　vibration　behavior.　Secondly　vibration-started　wind　speed　of　different　section　hanger　differs　with　each　other.　Thirdly　relation　between　vibration　amplitude　and　incoming　wind　speed　varies　obviously.　At　the　same　time,　numerical　results　are　compared　with　those　of　one　wind　tunnel　test　and　the　out　coming　is　satisfied.　Relation　between　vibration　amplitude　and　wind　speed　in　both　numerical　simulation　and　wind　tunnel　test　is　similar　because　vibration-started　wind　speed　in　numerical　result　has　only　10%　discrepancy　with　that　in　wind　tunnel　test　while　vibration　amplitude＇s　discrepancy　is　only　15%.　Consequently,　analysis　results　show　the　reliability　of　this　numerical　simulation　technique.