Abstract: With the pace of meteorological service information accelerated, more and more kinds of comprehensive meteorological observation and forecast data have been produced. To share meteorological data timely and effectively online, the meteorological information delivering system is established based on Flex and Rich Internet Application (RIA) which are of advantage in internet GIS. On the basis of user requirement and the construction target analysis, a general framework composed of four layers is proposed for the Meteorological Information Web Sharing System. The data layer on the bottom mainly stores meteorological data, geo spatial data and socioeconomic data, providing fundamental data for upper layers. The upper service layer consists of various GIS services, Web services and LiveCycle Data Service. Different data and application services will be sent according to different requests from presentation layer. The presentation layer is composed of visual Flex controls, including map display object, geometric object, functional object etc. This layer communicates with data service layer and interacts with the client layer. The uppermost layer is the client layer with Flash plug in installed for running SWF files. The features of the sharing system are introduced from six aspects, including basic geographic information displaying, meteorological data displaying, information querying, data downloading, spatial analysis on meteorological data, and web map plotting/outputting. Finally, four key issues related to this system are further discussed. The first one is data organization and management. Massive data of the system are stored and managed by category. For instance, the view of existing data based on old database structure is newly designed for management, obtaining a minimum dataset satisfying constraint in order to improve data access efficiency. With respect to meteorological data stored as a file form, spatial database is adopted. Meanwhile, all data is created following by meta data tables. The second issue is meteorological data conversion. Utilizing model builder technology, some complicated geo processing models as tasks are established, which can automatically accomplish data conversion, data generation and data loading. The task can be done as a batch job by customizing parameters of the model manager. The third issue is cache technology for map services. Basic geographic map and meteorological services are cached with different strategies to improve the display efficiency. The last issue is map display technology based on Flex. Due to combination ArcGIS API for Flex with features and special effects of Flex, the meteorological information delivering system is notable and interactive.In conclusion, Flex and Flash are feasible in meteorological information sharing field, improving the display efficiency of meteorological data in internet GIS. The advantages of this system comparing with the conventional Web GIS in meteorological field are discussed. This system can also bring a high performance meteorological information sharing platform based on network for emergency and public meteorological services. It can also lay solid technique foundation for constructing more effective meteorological information delivering system in nationwide.