This paper clarifies the mechanism of the dynamic characteristics of the water-lubricated bearing-rotor coupling system at different operating stages. Dynamic models of the water-lubricated bearing-rotor system under fluid lubrication are developed. The influences of different operating modules on the dynamic characteristics are investigated. The effects of different speeds, different loads, and different impacts are analyzed. The time domain responses, axis orbits, and phase diagram are gained. Velocity has impacts on the vibration performance of the shaft. The external load has slight effects on the vibration characteristics. Different forms of transient impacts have different effects on the vibration characteristics. The validity of the new-built models is verified by experiments. Results provide theoretical foundations for the optimum design for such bearing-rotor systems.