In　this　paper,　the　periodic　solution　of　hypersonic　functionally　graded　plate　subjected　to　aero-thermal　load　with　two　degrees　of　freedom　is　investigated.　Firstly,　the　average　equations　in　1:2　internal　resonances　are　obtained　by　using　multi-scale　method.　Based　on　the　Poincare　mapping　and　the　Melnikov　function,　we　get　the　sufficient　condition　for　the　existence　of　periodic　solution　about　the　system.　Then　we　obtain　the　phase　diagrams　of　the　solution　which　were　under　different　parameters　by　using　Matlab.　The　simulation　results　demonstrate　the　sufficient　condition　which　we　have　got　is　correct.　Finally,　by　using　the　integral　manifold　theory　and　average　method,　we　analyze　the　stability　of　the　periodic　orbit.