Over the years, the water resources development has played an important role in control of schistosomiasis transmission. Water conservancy projects, especially some mega-project construction in schistosomiasis endemic areas usually give rise to changes of the ecological environment in the project and downstream area. Some of ecological environmental changes rea conducive to control or elimination of schistosomiasis, but some ecological environment may lead to the spread of snails and schistosomiasis. It is, therefore, necessary to evaluate the effect of the water conservancy and anti-schistosomiasis project. Furthermore, hygienic evaluation of the under-construction large water conservancy projects are actively carried out by the health sector, and prevention and control measures are put forward according to the risk of snail spread in the projects. During the construction of the projects, the potential risk of snail spread can be reduced or eliminated as long as water conservancy and schistosomiasis control engineering measures are implemented, so as to achieve water conservancy, schistosomiasis control and other socio-economic comprehensive benefits. As to the research of prevention of snail spread, new technologues of snail hydraulic achievements have been incorporated into the Water Sector Technical Guidance file. At present, work of the water conservancy and schistosomiasis control is coming into institutionalization, normalization and standardization.