Topography and natural phenomenon are among effective elements in site- selection, dissemination, physical development and morphology of cities. Essential objective of this research is identifying natural restrictions of physical development in Sanandaj city, and obtain the best site for future developments. For achieving this goal we use topographic, geology and land use maps. Meteorological data, library sources and field studies have also been used. First of all we defined limitation of study area on the topographic and geological maps and then we used AutoCad Map 2004 and ArcInfo 8.0 software for digitizing, repairing of errors and creating topology layer of maps. We created database for maps by using GIS. We used spatial analyst extension to provide output.Then field studies started. Results showed that some factors such as Abidar elevation, hills inside the city and Gheshlagh river have made restrictions for urban development, so that less than 4.81 percent of district are suitable for urban development.