In order to study the characteristics of static stiffness of the machine spindle system, a spindlebearing system model of a highperformance machining center was established, which including the spindle rotor and the bearing. The components model of spindle system was built by the finite element method (FEM), composed with the quasistatic model of the ball bearing, the finite element model of the spindle system was obtained, and the static stiffness of the spindle system was obtained through calculating. The test experiment of static stiffness was carried out to verify the correctness of the theoretical calculation results. The results show that the theoretical calculations and the experimental results are corresponding quite well, so the accuracy of the FEM is proved. Besides, due to the damping effect and friction function inside spindle system, the unloading static stiffness is greater than the loading static stiffness. At the same time, certain amount of nonlinearity of axial static stiffness is existed.