Abstract: Based on the idea of sustainable development, this paper proposes a conceptional model called eco-economical model of environmental hydro-science. Thermodynamically speaking, it is a model of low entropy. Philosophically speaking, it is a model of combining nature and human into one and keeping them in conformity with the Great Harmony. In this model the environmental hydro-science is a new science newly developed in China, which deals with the interrelation between water resources and environment comprehensively and systematically. For the application, eight points of the above stated model are discussed detailly.