The　free　vibration　characteristics　of　a　cylindrical　shell　of　a　functionally　graded　three-phase　composite　are　investigated　under　arbitrary　boundary　conditions.　The　novel　three-phase　composite　is　composed　of　graphene　platelets　(GPLs)　in　the　form　of　functional　gradient,　carbon　fibers　with　different　layup　angles　and　epoxy　resin　matrix.　Firstly,　the　governing　equations　of　motion　for　the　cylindrical　shell　structure　of　the　three-phase　composite　are　derived　based　on　the　first-order　shear　deformation　theory　(FSDT),　the　Von-Karman　geometric　nonlinear　relationship　and　Hamilton＇s　principle.　Then,　the　natural　frequencies　and　mode　shapes　of　the　three-phase　composite　cylindrical　shell　were　discretely　solved　by　applying　the　Galerkin　method.　Finally,　the　accuracy　of　this　paper＇s　method　is　verified　by　comparing　it　with　Abaqus　simulation　results.　In　addition,　the　effects　of　GPLs　mass　fraction,　functional　gradient　form　and　boundary　conditions　on　the　intrinsic　vibration　characteristics　of　three-phase　composite　cylindrical　shells　are　analyzed.　©　2024　Journal　of　Dynamics　and　Control.　All　rights　reserved.