Based on the first-order shear deformation theory taking into account geometrical nonlinearity, initial geometrical imperfection, vibration and nonlinear dynamic analysis of the sandwich laminated composite panel characterized by a continuous thickness variation in thermal environment and resting on an elastic foundation are considered in this paper. Variable thickness could affect the design of composite panel since it allows to tailor the stiffness features in the most stressed areas within the domain, keeping the weight constant. As a consequence, an improved dynamic behavior of the structure may be exhibited. The motion equations of dynamic analysis are determined due to Galerkin method and the obtained equation is numerically solved by using Runge-Kutta method. In numerical results, the effects of initial geometrical imperfections and geometrical parameters, material properties, coefficients of foundation, mechanical loads, temperature and the variable thickness on the nonlinear dynamic response and vibration of the laminated composite panel are investigated.