Abstract: In engineering, as in science and the arts, evolutionary processes ultimately lead to simplification and perfection. The rise of modern small satellites show that the space technology is developing forward in this way.Because of the remarkable advantages of the small satellites, such as light weight, small size, low cost, high performance and short development time, expect:the development of small satellites will bring about a great revolution to satellite application and satellite technology.In this paper, the concept and background of small satellites were expounded at first. Secondly the survey of their development were made. Finally. the key technology of small satellites were studied.