An　analysis　on　nonlinear　vibrations　of　a　simply　supported　functionally　graded　materials　(FGM)　cylindrical　shell　at　its　two　ends　which　subjected　to　the　radial　excitation　in　the　uniform　thermal　environment　is　presented　for　the　first　time.　Materials　properties　of　the　constituents　are　graded　in　the　thickness　direction　according　to　a　power-law　distribution.　In　the　framework　of　the　First-order　shear　deformation　shell　theory,　the　nonlinear　governing　equations　of　motion　for　the　functionally　graded　materials　cylindrical　shell　is　derived　by　using　the　Hamilton＇s　principle.　The　Galerkin＇s　method　is　utilized　to　discretize　the　governing　equations　of　motion　to　a　five-degreeof-frecdom　nonlinear　system　under　combined　thermal　and　external　excitations.　By　using　the　numerical　method,　the　fivcdegree-of-freedom　nonlinear　system　is　analyzed　to　find　the　nonlinear　responses　of　the　FGMs　cylindrical　shell.　Copyright　©　2010　by　ASME.