Abstract: In order to promote the systematic and standardized development of water environmental carrying capacity (WECC) research in Liaohe River Basin, by reviewing the development process of WECC, the concept of WECC was differentiated and defined based on the connotation of water resource, water environment and water ecology (“Three Waters”). On this basis, following the three-level framework, a WECC index system based on “Three Waters” connotation in Liaohe River Basin was established which was composed of three core criteria layers of water resource, water environment and water ecology through basic research, index frequency analysis, policy implementation and expert recommendation. Finally, the development directions of WECC were analyzed concerning the basic theory research, technology and application in Liaohe River Basin in the future, which could provide support for scientific assessment, optimization of early warning and management application of WECC in Liaohe River Basin, and promote the sustainable development of socio-economy, water resource,water environment and water ecology in Liaohe River Basin in the future.