With the increase of domestic and foreign launching tasks, it is becoming a serious challenge that plenty of failure or invalid spacecrafts in the process of space resources recycling. The active debris removal can be regarded as an effective and fundamental means that can realize the reuse of space resources and safe disposal. The concept of active debris removal is clarified and its development process also is analyzed. Some key techniques, such as relative navigation, coordinated control, capture method and device for non-cooperative target, are proposed. It will provide some fruitful reference for our country′s active debris removal in future.