<p>The rotor system within the high-speed turbopump of a cryogenic liquid rocket engine is influenced by the effects of fluid inter-coupling in the gaps and the interaction among various components. The principal objective of this project is to investigate the mechanisms behind the evolution of dynamic behavior in the advancement of rotor systems designed for enhanced performance and operation under more extreme conditions. In the first place, taking into account the equations for fluid film thickness, dynamic Reynolds, lubricant performance, and the force balance of the support spring element, as well as the thermoelastic flow model for mechanical seals and the dynamic model for floating ring seals, the models are established. In the second place, by integrating the aforementioned models, a comprehensive dynamic model of high-speed turbopump rotor system, inclusive of the mechanical seal, floating ring seal, and rolling bearing has been explored. In the end, the numerical solution approach for the aforementioned dynamic model has been proposed, and the mechanism behind the dynamic characteristics evolution of the liquid oxygen turbopump system under quintessentially operating state has been discussed. The integration of the floating ring seals exerts minimal influence on critical characteristics, and it contributes to heightened transient responses and a reduction in unstable speed. The results will be of help to explain the dynamic characteristics evolution of the multi-component coupled rotor system, and offer a valuable reference for the related engineering application to ensure the stability and reliability operation of the high-speed rotor system.</p>