The　bifurcation　and　chaotic　motion　of　a　fully　simply-supported　thin　rectangular　plate　considering　nonlinear　deflection　subjected　to　axial　subsonic　airflow　and　transverse　harmonic　excitation　is　analyzed.　Based　on　von　Karman＇s　large　deformation　theory,　the　partial　differential　equation　of　motion　of　the　structural　system　is　formulated　using　Hamilton＇s　principle,　and　it　is　transformed　into　a　set　of　ordinary　differential　equations　(ODEs)　through　Galerkin＇s　method.　The　three-dimensional　(3D)　aerodynamic　pressure　induced　by　the　transverse　motion　of　the　plate　is　derived　from　the　linear　potential　flow　theory,　and　the　validity　of　the　aerodynamic　model　is　verified.　For　the　structural　system,　Melnikov＇s　method　is　adopted　to　give　an　analytical　expression　of　the　necessary　condition　for　the　chaotic　motion　of　the　plate.　The　influences　of　the　flow　velocity　and　the　external　harmonic　excitation　on　the　chaotic　motion　of　the　plate　are　investigated.　Numerical　simulations　are　carried　out　to　obtain　the　bifurcation　diagrams,　displacement　time　histories,　phase　portraits,　and　Poincare　maps　of　the　nonlinear　system　to　verify　the　validity　of　the　analytical　results.　The　results　show　that　when　the　flow　velocity　increases,　the　plate　will　be　unstable,　and　chaotic　motion　of　the　plate　will　occur.