Precision/ultra-precision machining technologies are the fundamental methods for achieving high form accuracy and surface quality. With the continuous development of modern science and technology, precision machines now involve complicated systems engineering and have been widely used in the production of components in various aerospace, national defense, optics, mechanics, electronics, and other high-tech applications. This chapter presents an overview of the conception, development and application of ultra-precision machining, and the typical structure of ultra-precision machines, the developments of ultra-precision machining technologies, especially ultra-precision cutting, ultra-precision grinding and polishing are also reviewed. The current state and problems of this field are analyzed, and the future development trend is prospected.