More than ten years’ large scale anti-terrorist activities and some material success do not mean the end of terrorism. The current international legal system has already touched upon terrorist issues，but the rules are not systematic，and rely highly on domestic law of some big powers as well as the balance of international politics. It is urgent to establish the illegal nature of “preemptive self defense”in international law，and limit the “war on terror”in the edge of tyranny，and to push forward the international community to solve the problem of terrorism in the track of rule of law. Specifically，states should cooperate in defining terrorism，establishing the substantive and formal principles of fighting against terrorists，perfecting the overall environment of international society. Only in this way，it is desirable that the world will have a peaceful and stable order.