The disc-shaft-hull-bearing system is widely applied in engineering, including aircraft engines, ship propulsion systems, and wind power drive systems. The influence of the hull on the coupled system is critical to its overall performance. In this paper, the finite element method and Hertz contact theory are employed to model the disc-shaft-bearing system and the disc-shaft-hull-bearing system. The influence of the hull on the vibration modes and amplitudes of the coupled system at various shaft rotational speeds is subsequently discussed. It is found that the introduction of the hull increases the degrees of freedom, and the interactions between the hull and other components make the coupling more intricate, leading to a more dispersed resonance region. Additionally, the hull forms a structure similar to a vibration absorber when combined with other components, such as spring connectors, effectively absorbing and dispersing vibrational energy, significantly reducing the resonance response. Notably, the axis orbits of the motor become irregular, exhibiting significant twisting and swinging at high rotational speeds. Finally, the schematic diagram and experimental platform for the disc-shaft-hull-bearing system were designed and constructed to validate the correctness of the model and code. The above research not only aids in understanding the dynamic behaviors of the disc-shaft-hull-bearing system but also provides theoretical guidance for optimizing the hull structure, improving system stability, and suppressing vibration and noise.