We　analyze　the　transverse　nonlinear　vibrations　of　a　rotating　flexible　disk　subjected　to　a　rotating　point　force　with　a　periodically　varying　rotating　speed.　Based　on　Hamilton＇s　principle,　the　nonlinear　governing　equations　of　motion　(coupled　equations　among　the　radial,　tangential　and　transverse　displacements)　are　derived　for　the　rotating　flexible　disk.　When　the　in-plane　inertia　is　ignored　and　a　stress　function　is　introduced,　the　three　nonlinearly　coupled　partial　differential　equations　are　reduced　to　two　nonlinearly　coupled　partial　differential　equations.　According　to　Galerkin＇s　approach,　a　four-degree-of-freedom　nonlinear　system　governing　the　weakly　split　resonant　modes　is　derived.　The　resonant　case　considered　here　is　1:1:2:2　internal　resonance　and　a　critical　speed　resonance.　The　primary　parametric　resonance　for　the　first-order　sin　and　cos　modes　and　the　fundamental　parametric　resonance　for　the　second-order　sin　and　cos　modes　are　also　considered.　The　method　of　multiple　scales　is　used　to　obtain　a　set　of　eight-dimensional　nonlinear　averaged　equations.　Based　on　the　averaged　equations,　using　numerical　simulations,　the　influence　of　different　parameters　on　the　nonlinear　vibrations　of　the　spinning　disk　is　detected.　It　is　concluded　that　there　exist　complicated　nonlinear　behaviors　including　the　periodic,　period-n　and　multi-pulse　type　chaotic　motions　for　the　spinning　disk　with　a　varying　rotating　speed.　It　is　also　found　that　among　all　parameters,　the　damping　and　excitation　have　great　influence　on　the　nonlinear　responses　of　the　spinning　disk　with　a　varying　rotating　speed.