Abstract: Based on the experience and existing decision-making procedures of flood control on the middle Yangtze River, a framework-design for developing the Yangtze River flood control decision support system (YRFCDSS) has been proposed, featuring by an appropriate system structure, advanced software design, excellent problem-solving abilities, good extensibility and compatibility to keep up with technical changes, and suitability for an efficient and flexible real-time management. The paper out lines an approach and some guidelines for developing YRFCDSS. The logic structure of the system was determined as follows: under supports of a data base and a knowledge base, the entire operational environment for the system was set up through the main control programs, realizing two main functions of in teractive information providing and flood control system simulation. To build YRFCDSS effectively, some key-techniques including GIS, graphical user interface, model managers, and other advanced human-computer in teraction were also addressed.