Purpose <p>The support is a key factor affecting dynamic performance of machine tool spindle, and rotor-bearing dynamic analysis is an essential issue for the design of spindle. However, advantages of traditional supports are not highlighted when they are utilized for the large-size machining spindle. To overcome this problem, this paper proposed an improved spindle with a water-lubricated hydrostatic thrust bearing and two types of rolling bearings, and then investigate the rotor-bearing dynamics for the improved spindle.</p> Methods <p>The rotor-bearing dynamic model for the machine tool spindle was established by integrating a 5-DoF rigid rotor dynamic model and the models of water-lubricated hydrostatic thrust bearing and rolling bearings. The steady-state dynamic performance of the spindle is analyzed systematically. An experimental prototype of improved spindle is developed to measure its dynamic performance.</p> Results <p>There exist 4 natural frequencies for the improved spindle in the study, the first order natural frequency decreases with an increase in the diameter of thrust disc of the water-lubricated hydrostatic thrust bearing. The axial stiffness of spindle can be improved by introducing a large-size water-lubricated hydrostatic thrust bearing, and the radial stiffness of the spindle can be improved by aid of the rotational stiffness of the water-lubricated hydrostatic thrust bearing.</p> Conclusions <p>The improved spindle supported by the water-lubricated hydrostatic thrust bearing and the rolling bearing shows high natural frequencies, large axial stiffness, high rotation accuracy and low temperature rise, it is promising that the improved spindle can be found an application in the high-speed face machining.</p>