<p>Accurately predicting the dynamic response of the turning hydrostatic spindle is the key to ensuring machining accuracy and achieving active bearing control. Therefore, in order to solve the problem of real-time changes in the dynamic characteristics of the spindle system caused by the removal of the workpiece material during the turning process, the dynamic model of the turning variable mass hydrostatic spindle system is established, based on the Rayleigh continuous beam vibration theory, the hypothetical mode method, and the Lagrangian equation. Effect of turning parameters on the time-varying natural frequency and the dynamic response under multiple-conditions are investigated through Eulerian numerical simulation. The correctness of the dynamic model construction and numerical solution is verified by experiments. The results show that the vibration response is the product of the time function and the modal shape function, and its variation law is basically consistent with the time function, but the vibration bias displacement increases due to the superposition of the mode shapes. The gain amplitude of the system time function is mainly affected by the turning force, and the growth relationship between the two is nonlinear. The natural frequency is decreasing as a whole, and the height and rate of decline increase with the increase of cutting depth.</p>