Abstract: To ensure the space safety, this paper proposes the theory of orbital game, including the related concepts, principles, and methods. Based on the mission scenario, 9 kinds of orbital game such as orbital latency, orbital camouflage, orbital pursuit-evasion, orbital interception, orbital defense, orbital blockade, orbital encirclement, orbital adhesion, and orbital take-over are defined and classified. The mission procedure for a common orbital game is designed. The frame for solving orbital game problems based on artificial intelligence and biological swarm intelligence are discussed. The methods here will be beneficial for the missions of surveillance, take over, operation, repair and clearance of noncooperative space targets.