The processing performance is closely related with dynamic performance and the dynamic performance is one of the most important performance indicators which is affecting the performance and product quality. The machine is affected most by the dynamic performance of machine bed. The modal analysis method is used to analyze the dynamic performance of the machine. In this paper, the modal analysis of lathe bed is conducted. A 3D solid model of HTC100 NC lathe bed is built with SolidWorks. In order to facilitate the finite element analysis, the model of lathe bed is simplified. The modal analysis of lathe bed is calculated with ANSYS Workbench 12. The first six natural frequencies and corresponding modes are obtained through modal analysis of the lathe bed. According to the low-order natural frequency and modal vibration shapes, the rigidity vulnerable area of lathe bed is realized, which provides the reliable theory to improve lathe bed structure.