The aim of this paper is to investigate the nonlinear free vibration behaviour of elastically supported carbon nanotube reinforced composite (CNTRC) beam subjected to thermal loading. The gradation of material properties in thickness direction of CNTRC are assumed as UD, FG-X and FG-Λ and are evaluated through a micromechanical model namely voigt (V) model. The bean is supported with two parameters Pasternak foundation with Winkler cubic nonlinearity. The higher order shear deformation theory (HSDT) with von-Karman nonlinear kinematics using modified C0 continuous model through Hamilton principle is employed to establish the integral form of the equation of motion of the beam. The dimensionless natural frequency for different volume fraction of carbon nanotube, amplitude ratios, CNTRC distributions, slenderness ratios, support conditions and foundation parameters is studied. The present outlined approaches are validated with the results available in the literature