Based on the analysis on the current situation of the administrative enforcement of water law in Nanjing waterway of the Yangtze River, the demands and targets of the management information system for the enforcement of water law are put forward. Basic information database of the waterway and the database of the departments which occupied the waterway are the core of this system. Technologies including WebGIS, computer network, and modern wireless communication are adopted to set up the enforcement system. The system is operated and managed on the basis of the administration department ' s intranet.