With the rapid development of manufacturing industry

additive manufacturing (AM) technology has attracted more and more attention in the world. Additive manufacturing has been rapidly developed and widely used in aerospace

industrial machinery

automobile electronics and other fields. The biggest theoretical challenge of direct energy deposition (DED) technology at present is the lack of a deep understanding of the inherent relationship between the process-microstructure-performance

and the lack of an effective and cost-effective online monitoring process in the actual production process. Therefore

the repeatability

uniformity and reliability of the products manufactured by DED are difficult to meet the increasing production requirements of industry. This article introduces the DED in the process of heatphysical mechanism of the process. On the basis of summarizing the changes in temperature

molten pool size and molten pool morphology during the manufacturing process

summarizes the research of AM based on DED of online monitoring in the stomatal monitoring

and points out the existing problems and future development direction.