Abstract: The concept of outer space military confrontation includes two parts. The first is militarizing artificial satellites to enhance the combat effectiveness of its own side. The second is utilizing ground-based or space-based weapons to attack the other side. As to the legal character, the outer space military confrontation constitute the "use of force" in accordance with the international law. And as to the legal basis, the right of self-defense exercised in the outer space provides the legality for the use of force in the outer space military confrontation. Based on the high possibility of outer space military confrontation developing into armed conflicts, besides the basic principles of international law and outer space law, the basic principles of armed conflict law should also apply to outer space military confrontation, including principle of limitation, principle of discrimination, and principle of proportionality.