Since the international water crisis intensified, transboundary water cooperation has become the key to resolving the water crisis and achieving peaceful and sustainable development among countries. This study built international transboundary water cooperation networks based on transboundary water agreements, and used social network analysis and other methods to examine the spatial and temporal structure of transboundary water cooperation from the global, intercontinental and national scales. The conclusions are as follows: (1) The number of international transboundary water cooperation projects increased from 1820 to 2017, and the scope of cooperation expanded significantly. The cooperation issue area changed from border issues and water quantity to joint management and water quality. The purpose of the agreements changed from regulatory to generative, procedural and regulatory. Multilateral cooperation and transboundary groundwater cooperation are the current development trends in international transboundary water cooperation. (2) During the same period, there were differences in the development process and focus areas of transboundary water cooperation among the five continents. Europe and North America were dominated by water quality, Africa and South America were dominated by joint management, and Asia had similar cooperation proportions in three areas: water quality, water quantity and joint management. Although the global transboundary water cooperation network covers more and more basins and countries, its coverage rate is still low. (3) The international transboundary water cooperation networks from 1820 to 2017 experienced three stages, namely, network formation, network expansion, and network differentiation. North American countries have a high degree of transboundary water cooperation, but due to geographical constraints, their cooperation targets are relatively single. After World War II, African countries have gradually dominated in the network. Since 1992, Asian countries have been increasingly active in the transboundary water cooperation network. The demand for transboundary water cooperation in Asian countries is growing. China, as a large responsible developing country, should strengthen transboundary water cooperation with neighboring countries, and actively promote transboundary water cooperation in Asia.