The rapid increase of human-induced environmental problems, especially the current situation in our big cities and the environmental pressure caused by them leads to destruction of our vital natural resources. With wrong land use decisions made on various scales, natural features are negatively affected, which can harm to humans and other livings and can compromise the sustainability of the natural structure. In this research, evaluations and analysis are made on land-use decisions and natural thresholds and two approaches of protective and prudence are opted for in order to carry out an assessment of natural threshold of Urla. District selected as the study area for this purpose, sets of data were taken into consideration in Urla district including conservation areas, grasslands, agricultural lands, forest areas, water surfaces and fault lines. All data are kept in a database in accordance with the rules of GIS (Geographic Information Systems) and the model generated through analysis of the natural threshold. As a result of these studies in Urla district, given the values of cardinality and density of that area, 57935.5 ha absolutely required to be protected, 3936.91 ha top priority area to be protected and 4781.89 ha areas which can be placed and can get other land use decisions. The areas were classified in three groups, and a 1/25 000-scale map of the synthesis and report were prepared. Spatial data produced as a result of this study, bear a significant base feature in controlling the compliance of existing plan decisions with natural threshold and future planning studies.