In order to estimate the static and dynamic characteristics of motorized high-speed spindle, the full parameterized FEM model of it is established and studied in the paper. After the FEM analysis of the spindle, the static stiffness, natural frequency and normal modes of vibration are obtained. Then, a design sensitivity analysis of some design parameters is conducted based on the finite element model to investigate their influence on the static stiffness and natural frequency of the spindle system. Through the sensitivity analysis, the optimal plan is proposed, the first natural frequency as the first objective function of optimization and the static stiffness as the second, which changes the objective function of multivariable into that of a single one. Therefore, it considerably increases the efficiency of optimization. The optimization leads to a noticeable improvement of static stiffness and first-mode natural frequency.