A GIS-based flood forecasting system for the Hanjiang River basin is successfully designed and developed on the basis of the Microsoft Visual Studio.NET environment and by means of embedded GIS technology and SQL Server. The system has a reasonable structure and preferable practicability. By analyzing the implementation objective, the system’s framework design, function design, relative key technologies and interface design are discussed emphatically. The system has good expansiveness and transplantation features and can provide an important technological support for flood control decision and integrated water resources management for the Hanjiang River basin.