Nonlinear　dynamic　analysis　of　a　cantilever　functionally　graded　materials　(FGM)　rectangular　plate　subjected　to　the　transversal　excitation　in　thermal　environment　is　presented　for　the　first　time　in　this　paper.　Material　properties　are　assumed　to　be　temperature　dependent.　The　nonlinear　governing　equations　of　motion　for　the　FGM　plate　are　derived　based　on　Reddy＇s　third-order　plate　theory　and　Hamilton＇s　principle.　The　first　two　vibration　mode　functions　satisfying　the　boundary　conditions　of　the　cantilever　FGM　rectangular　plates　are　chosen　to　be　the　admissible　displacement　functions.　Galerkin＇s　method　is　utilized　to　convert　the　governing　partial　differential　equations　to　a　two-degree-of-freedom　nonlinear　system　including　quadratic　and　cubic　nonlinear　terms　under　combined　external　excitations.　The　present　study　focuses　on　resonance　case　with　1:1　internal　resonance　and　subharmonic　resonance　of　order　1/2.　The　asymptotic　perturbation　method　is　employed　to　obtain　four　nonlinear　averaged　equations　which　are　then　solved　by　using　Runge-Kutta　method　to　find　the　nonlinear　dynamic　responses　of　the　plate.　It　is　found　that　chaotic,　periodic　and　quasi-periodic　motions　of　the　plate　exist　under　certain　conditions　and　the　forcing　excitations　can　change　the　form　of　motions　for　the　FGM　rectangular　plate.　(c)　2010　Elsevier　Ltd.　All　rights　reserved.