Abstract: In this paper, the development of small satellite technology over the past five decades is reviewed, including both traditional and modern small satellites, as being used for earth observation, navigation and communication, space technology experiments and demonstrations, deep space exploration, and in military domains, particularly, the breakthrough in high-resolution imaging system of earth observation small satellites. The orbital debris related with small satellites and the effects are discussed, together with some measures to protect against the debris. Finally, ten principles with regard to the future development of small satellite technology are proposed, and the general prospect of future applications of small satellites is commented.