Much of the country is arid and semi-arid and water as a limiting factor for human activities in these areas is considered. One way to overcome the shortage of water, the water is wastewater treatment. Construction of wastewater treatment plant is an environmental constructional- activity and proper disposal of sanitary waste water produced is its main purpose, which, if ignored, will lead to irreparable consequences.In this study, we tried to integrate GIS and multi-criteria decision-making systems Elster identify the most effective location for the construction of the plant. For this purpose, the data 7 parameters slope, geology, height difference to the city, vegetation, land use, communication networks, distance from the town were prepared in GIS environment using Analytical Hierarchy Process (AHP) and a comparison of weight each criterion was calculated weight classes, Expert Choice software layer.Next, the areas of limitation was removed. Using the analytical functions of GIS mapping of the area was determined for each of the criteria. Finally, the integration of acquired zoning maps based on the weight of the final map in the four classes of Bsyarmnasb AHP method to be unsuitable. The results showed that 8 percent of the area studied is very convenient.