The crisis of water resource has been one of the social and environmental problems of the globe, which would be the main barrier of the living and development of the society in the long period. In order to exploit and utilize the water resource in maximum extent, high technology is eagerly introduced into the exploitation and the using of water resource. Management decision support system water resource environemt is a rising research subject. It's foundation and application will help the administer improve the automation and science of water resource's decision, and make the limited water resource lastingly produce the maximum social economical and ecological benefit. The basis of establishment of management decision support system of water resource environment of Longkou is the technique of RS, GIS, DSS and the simulated model of water resource The structure's design and establishment of management decision support system of water resource environment of Longkou is stressfully introduced in this article. For example, the environmental condition of the system, the establishment of spatial database, the attributed database, the methodological database and the main function that the system have, including the function of query, forecast and simulated analysis, spatial analysis, optimized dispatch, dialogue between man and computer and long-distance visit.