The healthy landfill of urban waste, such as every other engineering project, needs basic information and careful planning. Choosing different factors leads to diversity in data layers, consequently the attempts to find adequate solutions and make correct decisions directs the decision makers to apply systems which not only have high accuracy but also are fast and easy to be used in operations. Today ''Geographical Information Systems'' (GIS) have the potentiality to be applied in environmental planning and engineering projects. In present study, in order to select sites for dispose of urban waste of Tabriz, in addition to SPOT images, the following data layers and maps have been utilized; the steep map of the area, the maps of land use, land slide, road network, soil, hydrographic, underground water, dominant wind aspect, and the layers related to the distance from city center, airports and other important suburban areas. The results of present research represents that the conditions in Boolean method has less certainty and regarding to definite limitations in this method, the sites selected according to Fuzzy have fewer parameters, however in studying the two Fuzzy methods applied in this study (OWA and WLC) it revealed that although Weighted Linear Combination (WLC) is simple, it has some deficiencies; one of them is "overestimating'', meanwhile Ordered Weight Analysis (OWA) ,by ordered weights, offers this chance to the decision maker to insert more important subjects which have greater role in site selection. Regarding to this ability the result of site selection by OWA has better resolution.