The ceramic material Si3N4 was applied for highspeed motorized spindle, and parametric design program of the spindle was developed by APDL language. Cutting load and stiffness along radial of the spindle were analyzed and calculated, and then its static deformation and stress distribution were analyzed through finite element method. Springdamping element COMBIN14 was used to simulate bearing support, and parametric model of the spindle was set up based on variable with support span. Static characteristics of the spindle was optimized through zeroorder method, then Von Mises stress caused by radial load was reduced and a more reasonable support span was calculated. Radial cutting stiffness of the ceramic motorized spindle was increased by 1229%, the working accuracy and stability of the spindle were improved effectively.