This　paper　presents　an　investigation　on　the　nonlinear　dynamic　behavior　of　three-phase　rectangular　composite　plates　made　of　cross-ply　macro　fiber　composites　(MFC)　in　the　polymer　with　graphene　(GP)　skins,　which　are　uniformly　dispersed　at　the　top　and　bottom　surfaces　of　the　plates.　According　to　the　mixture　rules　for　multi-components　of　composite　materials,　the　constitutive　laws　for　MFC-GP　composite　materials　can　be　obtained.　A　simply-supported　rectangular　plate　model　subjected　to　a　transversal　excitation　in　thermal　environments　is　considered.　The　governing　equations　are　formulated　by　using　the　first-order　shear　deformation　theory,　von　Karman　geometrical　kinematics　and　Hamilton＇s　principle.　The　Galerkin　approach　is　used　to　discretize　the　governing　equations　for　analysis.　The　vibration　frequencies　of　MFC-GP　composite　plates　with　different　modes　are　presented　and　the　case　of　1:2　internal　resonance　is　selected　to　be　investigated　here.　Three　different　coupled　forms　(i.e.　uncoupled,　weakly　coupled　and　strongly　coupled　cases)　of　two　vibration　modes　are　presented.　In　addition,　the　influences　of　various　parameters,　including　volume　fraction　of　graphene,　applied　voltage,　temperature　effect　and　external　excitation,　on　the　nonlinear　dynamic　characteristics　of　MFC-GP　composite　plates　are　also　examined.