Abstract: Humanity has made remarkable strides in space exploration, from spaceflight to landing on extraterrestrial planets such as Mars and the Moon. While achieving monumental milestones in aerospace endeavors, the growing demand for constructing extraterrestrial bases and repairing/replacing components of space stations and satellites has surged concurrently.Additive manufacturing（AM） technology, renowned for its design flexibility and manufacturing freedom, holds vast potential for in-space fabrication. However, extreme space environments—including vacuum, microgravity, particle radiation, and extreme thermal cycling—pose significant challenges to space-based AM technologies. Current research on space AM primarily focuses on non-metallic materials. This review systematically summarizes the types of space-oriented metal AM techniques, experimental methodologies and challenges faced during manufacturing processes and in-service performance. It aims to provide insights for future research and development in the field of space metal additive manufacturing.