The problem of optimization for the machine spindle was researched. A project seeking optimization design for the spindle by the complex method was proposed and the quadratic optimization was adopted to achieve optimization of the stiffness and volume. Picking points randomly was transformed into picking points "directively" for implementing the multi-objective optimization design based on the feature that objection functions of the span optimization is exactly constraint functions of the volume optimization. The results showed that the spindle structure was improved evidently and it possessed practical value in the engineering to some extent.