The rule of law is essential to international society just as it is to domestic order, but it is much more difficult to achieve on the international level. The fields of International Relations and International Law have engaged relatively little with one another. The interdisciplinary research demonstrates a number of contemporary trends that are often ill-addressed by scholars of either field including the increased importance of non-state actors and the ramifications of state weakness and state illegitimacy. A new paradigm of international relations is needed to be created based on international law . Through the angle of international law, the author tries to reflect the main arguments of the various theoretical approaches in international relations, and also calls for an interdisciplinary collaborated research agenda to address the contemporary international problems and build a global order in the globalized world of the 21st century. The analysis should shed some light on the trend of the ongoing interdisciplinary discussion between International Relations and International Law.