Many water information systems have different construction period and different goals which lead to the water information systems have a poor ability of data sharing and the function expansion is difficult. Water information systems are professional, the formation of information isolated island make it difficult to adapt to the requirements of the new way such as "based on water conservancy, comprehensive services" of hydrologic business. Using Web Service technology can shield the incompatibility of operating systems and applications software between the information isolated islands. On the basis of origin system, the paper built a new water information system model witch is friendly, has a low degree of coupling and is easy to expand. The new model can significantly enhance the ability of information sharing and community service between the water information systems.