Integrated River Basin Management (IRBM) involves the integration of the multiple uses of water, the integration of multiple properties of water: water disaster, water resources, waterways, water environment, water ecology, water landscape and water culture, and the integration of water by space: upstream vs downstream, left bank vs right bank. The main problems of IRBM within the Lancang-Mekong River Basin includes flood disaster, navigation and its impact to basin cooperation, contradiction between development and protection, and public security in a framework of cooperation and integration. It has been a general concern for Mekong countries to manage water conservancy engineering and coordinate water supply, navigation, fishery, power generation, and water disaster management. All stakeholders put great emphasis on water conservancy engineering management in terms of basin planning, domestic and cross-border project construction, and cooperation mechanisms. In order to ensure the sustainable use of water resources, a series of continuously updated plans were proposed. Those plans set goals and provided measures for the rational and sustainable development of the resources in the basin, and meanwhile, it also put forward a mechanism to offset the adverse effects. The development of international navigation has deepened win-win cooperation, strengthened regional economic exchanges and tourism development, promoted regional prosperity among China, Laos, Myanmar and Thailand. The basin has abundant fishery resources and has the world’s third most diverse fish population, with 1,148 fish species, after the Amazon and Congo River Basins. Mekong countries have different needs for the development of fishery resources due to their different geographical locations and economic development, and thus very little cooperation in fisheries has been carried out among Mekong countries. The basin’s ecohydrological management involves environmental flow, water quality, soil erosion and sedimentation, aquatic organism and underground water protection. The current measures include enhancing monitoring, scientific assessment, rational regulation of water system, the establishment of natural reserves, and international cooperation. Climate change and construction of dams are both critical challenges faced by the basin in terms of ecohydrological management in the 21st century.