Application on material remove of ultrasonic is mostly processing vertically to brittle material, this is because vertical vibration energy can direct passing tool to utilize grit to move the material on the workpiece. If want to mill workpiece, vertical vibration energy certainly must be changed into a side direction (horizontal) vibration and then the vibration energy will to conform to processing need. The purpose of this research is to utilize the ultrasonic energy theory collocate Finite Element Method (FEM) for tool design of milling. Hope that can reach the best processing efficiency. Additionally, we will change the existing vibration system in order to expect under the same condition to bring the greastest efficiency.