The theory of structural dynamic analysis is put forward in this paper. The dynamic performance of a precision machine tool bed is analyzed by means of finite element method, and the analysis result shows that the natural frequency is too low is the main reason of the vibration of the bed. In order to improve the dynamic performance of the bed, the dynamic performance of the unit structure of the precision machine tool bed is analyzed. Based on the analysis of the unit structure, two structural optimization schemes for the machine tool bed are obtained. Furthermore, two optimization schemes are analyzed by means of finite element method too. Compared to the original machine tool bed, the dynamic performance of two structural optimization schemes is significantly improved.