Manufacturing of Metal Parts by 3D Printing Technology, as the greatest advanced and potential technology, presents the most important direction of Modern Advanced Manufacturing Technologies. With the development of science and technology constantly demand for materials, utilizing the Rapid Proto-typing Technology producing metal functional parts directly will be the main research directions. 3D printing technology is rapidly changing our traditional mode of production and way of life. 3D printing manufacturing technology, which is networked and personalized, will drive the third industrial revolution. Laser Engineered Net Shaping (LENS), Selective laser melting (SLM) and Electron Beam Melting (EBM) are the typical representative of the metal parts 3D printing technology. Based on the three types of technologies, this paper gave an overview introduction on metal 3D printing technologies, which include the basic constitution of equipments and fabricating principles. Then, the application fields of metal 3D printing technologies were introduced. At last, the development prospects of them were discussed.