Based on the classical plate theory，the large-scale vibration problem of functionally graded circular plates subjected to thermal loading is studied. The nonlinear motion equation of the functionally graded circular plate is derived by using the physical neutral surface concept under the classical plate theory. The Ritz-Kantorovich method is used to eliminate the time variable，and the nonlinear motion equation is transformed into a set of nonlinear ordinary differential equations with respect to the spatial variable. The available equations are solved on the basis of the shooting method，then the static response of the functionally graded circular plates under thermal loading and effects of amplitude，material gradient parameters，thermal loads and boundary conditions on the vibration behavior of the functionally graded circular plates are analyzed. The results show that the vibration response of peripheral clamping and simply supported FGM circular plates，as well as its linear and nonlinear vibration behaviors，change significantly under the influence of the thermal deformation. The heat-buckling deformation plate hardens within a limited range，and the inflexibility of the FGM circular plates will be reduced by excessive thermal buckling deformation as well. Therefore，the effect of thermal deformation on the vibration response of the FGM circular plate is complicated.