Abstract: The ram has a significant influence on the machining accuracy of the vertical five-axis machine tool. In order to improve the static and dynamic characteristics of the ram, a multi-objective genetic algorithm optimization based on the central composite design is proposed in combination with the arrangement of the ram ribs. On the basis of the original ram structure, five different rib layout structures were designed. The parametric model was established in SolidWorks, and the total deformation, first-order natural frequency and mass were used as evaluation indexes. Statics and modal analysis were carried out in Workbench. The well structure was selected as the optimal scheme by comprehensive analysis of finite element simulation data. The sensitive size was obtained by sensitivity analysis and the Central Combination Design was carried out. The response value of the test point was obtained in Design-Expert. The response surface model was built and the multi-objective optimization of the well ram was carried out. The optimization results show that the maximum total deformation of the ram decreases by 23.25% and the first-order natural frequency increases by 10.89% when the total mass increases by 3.32%.