As the important component of the machining tools，pillar has directly influence on the machining accuracy.Between the pillar and slide, the joint surface has a significant effect on the dynamic characteristic of the assembly structure.With the nodal pressures of the contact surface obtained through the static analysis as bridge the fractal model and the APDL finite element analysis method,which were combined to predict the dynamic characteristic of the pillarslide system. The natural frequency and corresponding vibration mode of the system considering the combined surface were obtained to complete the dynamic performance analysis of the columnsliding seat system, thus providing a theoretical basis for the design and optimization of the structure.