Abstract: In order to establish an accurate dynamic model of ball screw feed system and analyze its time-varying characteristics, two methods based on multi-objective optimization are proposed to obtain the parameters of the virtual material model of the joint, and the two methods are verified by experiments. The results show that the method based on the multi-objective optimization to obtain the parameters of the virtual material model of the whole joint is computationally expensive, but the operation is simple and the parameters are more reliable. Although the table load quality influences the natural frequency of the feed system, it is not as good as the effect of the nut position on the natural frequency of the feed system.