Abstract: Geography Information System (GIS) is a decision support system,and its primary characteristic is relevant to the deposited and processed information by geographical coding,including spatial,geographical location and attributes of the land objects as to the location. The authors discussed the general application patterns of GIS in hydrology and water resources. Using relaxed combination mode of GIS and hydrological models,the GIS platform of water cycle of the Yellow River Basin was established with MS-Visual Basic visualized developing language based on one component of ESRI-MapObject GIS. The background relational database,i.e. MS-Access database, was used to construct the GIS platform of water cycle of the Yellow River Basin,automatically linking to the foregrounding interface of GIS. All kinds of data related to water cycle of the Yellow River Basin, including original data set,mid data set and ultimate data set were saved in the platform with uniform coordinate and uniform format,which supplied data support for the study of water cycle elements and process of the Yellow River Basin.

Key words: MapObject, platform of attribute database, platform of GIS, the Yellow River basin