Abstract: The water dispatching below Sanmenxia resemvir is a non-structural and multiple-objective problem dealing with which deals with plenty of sectors and regions and is of storng spatially distribution information.With application of space analysis sub-system based on GIS,the space analysis and space description are realized,therefore the decision support functions are greatly enhanced.This paper presents the space data rmdel,the components,function and utilization of the space sup-system etc.