Abstract:PROE and ANSYS Workbench platform were selected for parametric modeling of the vertical column structure of VL855 type machining center. The Static Structural and Modal analysis were carried out. Through sensitivity analysis, the column wall thickness、the boss thickness of guide surface、inner rib thickness and bolt slot pitch were selected to optimize the design variables. Multiobjective optimization was applied by taking the weight, the maximum deformation and the first stage vibration mode of the column as objective variables. The results show that the weight of column is decreased by 52% after optimization. The column deformation is close to the deformation before optimization in the same load case, and the lower stage modes are improved in a certain extend, which meet the dynamic requirements in working condition.