In recent years, Western international institutionalist theory has taken new research directions: one is the turn to organizations, i.e., from studying international institutions to studying international organizations; the other is the turn to governance, i.e., from studying international institutions to studying institutional governance and global governance. These turns of international institutionalist theory provide new opportunities for interdisciplinary cooperation. From the perspective of interdisciplinary research, the theories, ideas, and methods of international law studies can help to explain the impact of the research turns, to improve institutionalist theory, and to elevate our ability to understand global affairs and tackle global problems. Meanwhile, it proves that international law studies have played a role in the research turns of institutionalist theory.