Abstract The nonlinear eigen frequency response of the functionally graded single-walled carbon nanotube reinforced sandwich structure is investigated numerically considering the Green-Lagrange nonlinear strain under uniform thermal environment. The mathematical model of the sandwich plate has been derived using the simple higher-order shear deformable kinematics including the temperature dependent properties of each constituent. The sandwich panel constitutes of graded carbon nanotube face sheets and homogeneous core. The desired nonlinear finite element solutions are obtained via the direct iterative method. Based on the necessary validation and convergence new results are computed for different design related parameters and discussed subsequently.