<p>By utilizing targeted energy transfer (TET) technique of nonlinear energy sink (NES), the structural vibration and noise in broadband low frequency can be effectively controlled, and the suppression effect of NES varies depending on the structural forms. In order to apply this technique to the vibration suppression of automotive panel structures, a coupled system with two degrees of freedom (DOF) comprised by the first-order modal of a simplified rectangular automotive panel and a NES structure, is established. The TET characteristics of the coupled system under forced vibration are analyzed. The slow invariant manifold (SIM) is utilized to predict the suppressed amplitude platform for the frequency responses of the coupled system, and the threshold interval of optimal TET is analytically obtained, which are validated by the numerical analysis. Then, in order to reduce the excitation level and the suppression platform, an intelligent optimization algorithm is utilized to comprehensively analyze and optimize various parameters of NES. Based on structural improved NES structure, the thin panel vibration suppression characteristics under different NES systems, including a parallel two DOFs NES system, a series two DOFs NES system and a NES system with segmented stiffness characteristic, are studied. The vibration suppression effects of three different NES structures on thin panel vibration are analyzed and compared. The vibration suppression performance and robustness of NES systems against initial conditions for low-amplitude vibration of the thin plate are further enhanced. The results of this study are beneficial for the application of NES technology in the low-amplitude vibration suppression of automotive panel structures, thereby expanding the engineering application fields of NES.</p>