With the development of space robot and rendezvous docking technologies,on-orbit servicing is expected to play an increasingly important role in spacecraft life-extension,capacity improvement and space debris removal.So far, the spacecrafts already existed in orbit and the space debris are generally non-cooperative,i.e.neither any artificial marks used for the measurement nor grappling fixtures applied to the capture are mounted on the target.Therefore,robotic onorbit servicing for non-cooperative spacecrafts has been a hotspot of research in recent years.In this paper,firstly,the characteristics of the on-orbit servicing for non-cooperative spacecrafts are analyzed,and the possible apphcations of mis technology are introduced.Secondly,the achievements of the main space powers are reviewed,and the key technologies of non-cooperative on-orbit servicing are summarized.Finally,the research prospects are presented.