Abstract: Metal additive manufacturing has attracted extensive attention from academia and industry in recent years， and has become one of the important development directions in the field of additive manufacturing. This paper systematically sorted out the development history of metal additive manufacturing technologies, and focued on introducing three mainstream processes: laser powder bed fusion, electron beam melting and directed energy deposition. On this basis, the forming principles of these technologies were described, and a comparative analysis of their advantages, limitations and typical application scenarios was conducted. From the perspective of the complete metal additive manufacturing process chain, key technical aspects involved in pre-processing, manufacturing, and post-processing were further discussed. Through representative case studies, the application potential and technical advantages of metal additive manufacturing in aerospace, healthcare, and automotive manufacturing were analyzed. Finally, the main challenges facing metal additive manufacturing and its future development trends were summarized.