Abstract: On the basis of accurately considering axial extension and transverse shearing, geometrically nonlinear governing equations for composite sandwich beams with elastic supports subjected to thermal loads are formulated. By using a shooting method, the two-point boundary value problem for nonlinear ordinary differential equations is solved numerically and the numerical solutions to static thermal post-buckling and thermal bending deformation of the sandwich beams with pinned-fixed ends under transverse uniform thermal loads are obtained. Curves of critical buckling temperature versus foundation stiffness parameters are plotted and mode transition feature is given. Thermal post-buckling equilibrium configurations of the beam in the first mode for different values of foundation stiffness and thermal load are analyzed.