In order to determine optimum landuses (in accordance with natural capability) and improve the current land management, landuse planning process was applied by using GIS. Within the framework of SYSTEM analysis approach basic ecological and socio-economic data were mapped. The mapped data were digitized and imported to Idrisi and Arc/Info, to build a Database, along with other descriptive data. The process of GEOGRAPHIC coordinates registration, building topology and editing the maps were done in Arc/Info. Then, in the analysis stage, Digital Elevation Model (DEM) was prepared using contour map in Idrisi. Based on that, slope, aspect and elevation maps were produced. In the middle stage of the analysis, environmental units map and units attribute table were made by overlaying slope, elevation, aspect, soil and vegetation type and density layers in Arc/Info. Then, environmental units attribute table was completed by considering other ecological and socio-economic data in ArcView. Specific ecological models were supplied for Dadghan basin and using Structured Query Language (SQL), each of environmental units capability was determined and mapped for alloted landuses. In the last analysis and landuse planning process stage, the priority of suitable landuses (in accordance with natural capability) was determined and mapped by cosidering landuse prerequisites and using SQL. Finally, in order to predict institutional, organizational and executive arrangements, criteria and regulations of establishing optimum landuses were presented together with buffers criteria and executive-organizational framework of basin management plan.