This　paper　presents　the　stability　and　bifurcation　analysis　of　a　simply-supported　functionally　graded　materials　(FGMs)　rectangular　plate　subject　to　the　transversal　and　in-plane　excitations.　A　two-degree-of-freedom　nonlinear　system　of　the　FGM　plate　is　obtained　via　the　Hamilton＇s　principle　and　the　Galerkin　approach.　The　case　of　primary　parametric　resonance　and　1:　2　internal　resonance　is　considered.　The　asymptotic　perturbation　method　is　utilized　to　obtain　four-dimensional　nonlinear　averaged　equation.　With　the　aid　of　Matlab　and　normal　form　theory,　the　various　types　of　dynamical　behavior　in　the　neighborhood　of　a　kind　of　degenerated　equilibrium　point　are　investigated.　It　was　found　that　static　bifurcation　and　Hopf　bifurcation　exist　for　the　FGM　rectangular　plate　under　certain　conditions.