Additive manufacturing in space has shown obvious advantages in several fields such as on-ground or in-situ manufacturing， space supplies，reducing spares and transportation, emergency response and promoting deep space exploration. This paper analyzes and discusses the application requirements and modes of the additive manufacturing (AM) in space. Based on the investigation of the current situation, technical plans and the potential development of AM in space, combined with the actual requirements of China’s space station and deep exploration, this paper defines the space AM application environments into three categories: on ground, in-situ(in cabin and in orbit)and planet surface. The detailed analysis of all potential application modes of space AM in each environment category is carried out. In addition, the research progress of AM in space is described in brief and the key technologies are analyzed in detail in order to provide important reference for the development route of additive manufacturing in space.