Purpose <p>Numerous structural parameters of rotor systems in engineering machinery are subject to uncertainties. For instance, parameters like the eccentricity and phase of aircraft engines and gas turbines show considerable variations and uncertainties, complicating the evaluation of the system’s dynamic characteristics.</p> Methods <p>To investigate the influence of uncertain parameters on the vibration characteristics of a multi-disk rotor-bearing system, this study considers several factors including the deformation of bearing seats, Hertzian nonlinearity, clearances, eccentricity, and initial phase. A nonlinear dynamic model of a three-disk rotor-bearing system is established, and the numerical vibration responses were compared with experimental data to validate the effectiveness of the model. The impact of uncertain parameters on the system is investigated using the Monte Carlo method.</p> Results <p>The results indicate that uncertain parameters, such as eccentricity, phase difference, and bearing clearance, have a significant impact on the vibration behavior of the system, particularly on the second-order resonance and non-resonance intervals of the system. Therefore, it is important to pay attention to the influence of these parameters on the vibration of rotor-bearing systems in high-speed rotating machinery equipment.</p>