Dental CAD/CAM, scanners and 3D printers are entering the dental market. Because of the digitization of these dental devices, the development of a auto dental preparation prototype machine can make teeth preparation and restoration in a single day because the machine can perform more precisely. We designed a a scara robot to develop a robot for automatic dental preparation. Vibration Analysis and Simulation of optimization were performed for predicting resonance phenomenon and minimizing deflections and volume. The purpose of the automatic dental preparation is to prepare teeth more accurate and faster than conventional method. After the completion of the production in the future, transfer precision and repeatability precision will be measured, and the tooth removal test will be conducted for dental models.