Static stiffness of a vertical machining center was researched based on fine experiment and finite element method. Static stiffness of three directions and deformation of the main parts were measured. Deformation of the spindle box was measured and detailed analysis was taken. Deformation of the joint between spindle box and column was measured. The results showed that weak leak of the joint is y direction. Finite element model of the machining center was established in Workbench and accuracy of the model was verified compared with experiments.