The overall design of the system and the implementation of key technologies are introduced. Using the new generation meteorological communication system and storage technology, the system realized the collection, monitoring, quality control, storage, and sharing of real time meteorological data, which covers 703 national automatic meteorological stations, more than 12000 regional automatic stations, etc., of meteorological service in 12 provinces (cities) over the Yangtze River Catchment. Meanwhile the system fills the requirements of high efficiency and high quality on the data monitoring and analysis. Taking advantage of the historical and real time meteorological data in the Yangtze River basin, the rainfall monitoring on fixed time scales such as day, month, season, year and so on or any period time is achieved, and using the method of statistical physics, the spatial distribution of precipitation in different seasons over the Yangtze River basin is extracted. Using the WebGIS framework based on Flex technology, the real time analysis of human computer interaction is achieved to meet the quick response of high density automatic stations under a multi user concurrent condition. The system provides an integrated operational application system combining the collection, collation, processing, analysis, product displaying and so on of meteorological information together for the Three Gorges Cascade Dispatching Center, and provides technical support for hydro meteorological service in the integrated scheduling and developing of upstream water resources.