Tool wear is a major issue in ultrasonic machining and it is more significant in case of micro-ultrasonic machining. Because of the size of the tool in micro domain; the strength is relatively poor and hence more tool wear results. Generally, in the off-line methods, tool wear is measured after machining and by the removal of the tool from the machine tool. However, it is difficult and untidy process to remove the tool for each measurement and reinstall it on the machine. In this paper a simple technique ‘Reference Point’ method has been proposed to assess the linear tool wear on the machine itself. A comparative study of tool wear in case of solid and hollow tool was made while drilling silicon wafer. Static load was considered as a process parameter. Surface topography and fracture mechanism are discussed with the help of scanning electron microscope (SEM) micrographs.