In this work, the key technologies of Micro Machine Tool (MMT) are discussed in detail. A three-axis MMT prototype is developed. It is driven by ultra precision linear motors with high resolution linear encoders as feedback. It is equipped with a high speed electro-spindle and an CCD stereo microscope as a monitoring device. Meanwhile, the entire machine is controlled with an open numerical control system based on motion controller. The Human-Machine Interface (HMI) software is developed with G code compatibility. At last, the evaluation tests have been done on the MMT, and the results are very satisfactory and show its excellent performances.