In order to improve the staticdynamic characteristics of whole machine effectively, with XK719 CNC milling machine structure as the research object, the finite element analysis method was used for modeling, analysis and optimization of the whole machine. Firstly, the harmonic response analysis was carried out. The analysis result shows that the first and second frequencies are 38 and 48 Hz, respectively. Secondly, sensitivity analysis was applied to the wall thickness of the parts and components of the machine tool, and the key dimensions related to first and second order frequency were found out. The result shows that on the whole machine almost the same, the quality of the first order natural frequency increased 11%, the second order natural frequency optimization results of increased by 12%. This design method can provide reference for the rapid design of the machine tool.