An　analysis　on　nonlinear　oscillations　and　chaotic　dynamics　is　presented　for　a　simply-supported　symmetric　cross-ply　composite　laminated　rectangular　thin　plate　with　parametric　and　forcing　excitations　in　the　case　of　1:3:3　internal　resonance.　Based　on　Reddy＇s　third-order　shear　deformation　plate　theory　and　the　von　Karman-type　equations,　the　nonlinear　governing　partial　differential　equations　of　motion　for　the　composite　laminated　rectangular　thin　plate　can　be　established　via　the　Hamilton＇s　principle.　Such　partial　differential　equations　are　further　discretized　by　the　Galerkin　method　to　form　a　three-degree-of-freedom　coupled　nonlinear　system　including　the　cubic　nonlinear　terms.　The　method　of　multiple　scales　is　then　employed　to　derive　a　set　of　averaged　equations.　Through　the　stability　analysis,　the　steady-state　solutions　of　the　averaged　equations　are　provided.　An　illustrative　case　of　1:3:3　internal　resonance　and　fundamental　parametric　resonance,　1/3　subharmonic　resonance　is　considered.　Numerical　simulation　is　applied　to　investigate　the　intrinsically　nonlinear　behavior　of　the　composite　laminated　rectangular　thin　plate.　With　certain　external　load　excitations,　the　simulation　results　demonstrate　that　the　nonlinear　dynamical　system　of　the　composite　laminated　plate　exhibits　different　kinds　of　periodic　and　chaotic　motions.