In order to promote development of economy of Poyang Lake region and provide the information of rainfall and flood regime promptly for all levels of departments, the author firstly has designed the project for the system, which includes six modules; secondly has developed and established the system based on ArcGIS by the language of Visual Basic which is object-oriented and visual, the technique of COM which is the current software development technique at present and SQL Server2000 as database server; at last the system has been applied in Poyang Lake area. The application has evinced that it can be used to query real-time and historical information of rainfall and flood regime conveniently and give help for front office to make right project for flood control, which will decrease casualty and property damage to the max.