The mechanical properties of ball screw pair are studied. The 3D model is established by SolidWorks. In ANSYS Workbench software, the modal, harmonic response and static structure finite element simulation of the ball screw pair are carried out, and the modal vibration mode, harmonic response curve, equivalent stress, strain nephogram and safety factor of the ball screw pair are obtained. The ball screw pair and nut are optimized, and the ball number and trajectory modeling of the ball screw pair are optimized, This paper explores the optimal solution of the influence of the number of balls on the overall performance of the ball screw pair, and provides some reference for the structural design and performance optimization of the ball screw pair.