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As for the machine tool with high-speed ball screw feed system, the quite large friction force may change the real contact state of kinematic joints, which would further affect the dynamic characteristics of the whole system. In this article, an equivalent dynamic model of high-speed ball screw feed system was established using hybrid element method. The equivalent axial stiffness of individual kinematic joint and system transmission stiffness were all derived considering the influence of feed rate. The variation in the system natural frequency with feed rates was analyzed using the model proposed and also verified by experiments. The results show that the system natural frequency in motion state is larger than that in static state and behaves differently in different feed rates. The equivalent axial stiffness of the rear-end support bearing unit can reduce to 0 as the feed rate increases, which further leads to a critical value for system natural frequency. In the high-speed motion of the feed system, resonance may occur when the system natural frequency is almost same to the torque ripple harmonic frequency of the servo motor.