Abstract: Spacecraft revealed a trend of large size and longer service time with the development of space exploration in the recent years, which result in a large quantity of tasks involving assembling, repairing and maintenance in out space. Welding technology, as a space processing technology with obvious advantages, shows promising application in the future. The background of space welding was introduced and the effect of special space environment on welding was summarized in this paper. The research status of welding methods for space application was emphasized and the ground simulation means as well as the related facility was analyzed. Finally, development of space welding was prospected. Ground base simulation facilities, space welding equipment and remote welding technologies are the main tasks to be solved urgently.