Abstract: The static and modal analyses of the motorized spindle were carried out by NewSpilad software to explore the influence of bearing preload and spindle extended length on the stiffness and natural frequency of the spindle. The results show that adjusting the bearing preload has little effect on the radial stiffness of the spindle, with a change of less than 20%. The axial stiffness has a large influence, and the change amount is more than 50%. The effect on the intrinsic frequency of the spindle is small, and the maximum change is 24%. Increasing the overhang has a small effect on the axial stiffness of the spindle, with a change of 5% or less. The effect on radial stiffness is larger, and the change amount is about 13%. The first-order intrinsic frequency has a tendency to increase. And verified by the spindle static and dynamic accuracy test. Comparison found that the error between the finite element analysis results and the actual test results is within 10%. The results of this study provide a theoretical basis for the spindle static and dynamic characteristics analysis, and further enhance the spindle design and development capabilities.