The performance of spindle system of machine tools directly affects the characters of machine tools. The static and dynamic stiffness of spindle system is one of the main factors that affect the machining precision of machine tools and the performance analysis of spindle system occupies an important position in the design of machine tools. Based on ANSYS, this paper analyzed static stiffness, vibration characters and harmonic response of spindle system of SSCK63-400-typed CNC lathe. Selecting improving the characters and saving the cost of spindle as optimization object and using APDL of ANSYS, the optimization of the spindle is completed by the optimization tools of ANSYS. This research provided the basis for statics and dynamics design of spindle system, shortened the design period and improved the design efficiency.