In supply-oriented water development, water is a rigid constraint on sustainable development in many parts of the world, especially in arid and semi-arid areas. The water resources carrying capacity (WRCC) concept represents the maximum socio-economic scale that can be supported by water exploitation without causing an irreversible impact on the ecosystem. In this paper, three-level framework is put forward to illustrate and quantitatively evaluate the WRCC. The first level is the principal body, which focuses on the study of water resources systems. The second level is the carried object, including the socio-economic system, water ecological system, and environment system. The third level is the coupling of the principal body and carried object to calculate the WRCC. This three-level WRCC model was applied to the load conditions of the Shiyang River Basin (SRB). The results show that the SRB is overloaded, and only 1.99 million people can be carried at the modern carrying level. The WRCC could be increased by optimizing industrial structures and improving water efficiency. This method provides a tool to help policymakers develop sustainable approaches to environmental management and planning.