This　paper　mainly　studies　the　physical　model　of　thermonuclear　reaction　in　Tokamaks,　analysis　the　L-mode　to　H-mode　transition　near　the　plasma　edge　in　Tokamaks　by　using　the　theory　of　nonlinear　dynamics.　Obtaining　the　averaged　equations　by　using　the　method　of　multiple　scales,　we　not　only　make　some　dynamics　analysis　for　unperturbed　and　perturbed　system,　but　also　give　out　parameter　bifurcation　diagrams　and　diagram　composition　about　bifurcation　of　multiple　limit　cycles　for　Tokamaks　system.　©　2011　IEEE.