The size and accuracy of the micro-structure is determined by the performance of micro-milling tool. To reduce the tool vibration and improve the machining quality, research on the mechanical characteristics of micro-milling tool is necessary. Finite element method was used to research the mechanical characteristics of micro-milling in this paper. By Mode and Static Analysis, the natural frequencies and mode shapes of various structure of micro-milling cutter was studied. The stress and deformation characteristic, including the influence, was also studied. Finally, the suggestion of optimal structure was supplied.