Abstarct: Abstract Water is one of the most essential factors for the development of human societies and the human environment. In recent years, due to the environmental and geographical changes, the significant reduction of atmospheric precipitation, the development of urban areas and construction on underground water tables, the excessive use of underground water and the increase in population, the city of Shiraz has There is a severe shortage of water resources. In this research, we first received the effluent output of the Shiraz treatment plant, and also determined and prepared a map of the uses around the treatment plant, which includes agriculture, industries, etc. Then, in the next step, we have prepared an electronic questionnaire to determine the best option for re-use, and together with the output results of the treatment plant and national and international standards for re-use, we have provided the environmental experts and specialists, and after Completing the questionnaire and determining the importance and ranking of the uses in order to summarize and prioritize the best option of reusing the treated effluent of Shiraz water treatment plant through the process of hierarchical analysis using the software (Expert Choice) and finally the option of agriculture It has obtained the highest rank in relation to the overall goal and has been determined as the first and most appropriate option for reusing the sewage of Shiraz city in the matter of decision making and choosing the best consumption option, and after that green space, industrial space, and tourism recreation respectively. and feeding the underground water table. This decision-making method can be very effective and useful in the decision-making and policy-making of wastewater treatment managers.