<p>This study breaks away from the traditional paradigm of linear primary structures, focusing on vibration suppression of nonlinear primary structures subjected to randomly disordered periodic excitation. Through in-depth analysis of the dynamic response mechanism of a nonlinear oscillator coupled with nonlinear energy sink (NES), we reveal the nonlinear stochastic vibration characteristics and optimize the parameters of the NES-controlled systems to achieve high-efficiency vibration reduction. First, a novel theoretical framework is proposed to determine the frequency response of stochastic systems by combining the complexification-averaging method and stochastic perturbation theory. Then, the vibration mitigation performance of the system is quantified by analyzing the transmissibility. Meanwhile, the influence of stochastic system parameters on the transmissibility is explored. Based on the criterion of minimizing the overall transmissibility, the optimal parameter configuration is determined. This configuration reduces the response amplitude of the NES and suppresses the loop structure, achieving a significant attenuation of the vibration amplitude across the entire frequency band. Finally, by comparing the dynamic response characteristics between the optimal and general parameter configurations under both deterministic and random excitations, it is found that the optimal parameter configuration effectively enhances the robustness and vibration suppression performance of nonlinear systems. Moreover, the analysis reveals that the randomly disordered periodic excitation is a key exogenous factor that induces irregular system motions. These results provide theoretical support for the application of NES in nonlinear vibration control and furnish guidelines for parameter optimization.</p>