ABSTRACT This paper is aimed at selecting optimum route of gas pipeline over three other recommended routes in Fars state by exploiting MCDM. The main criterias used here, include technical and engineering, environmental and socio-economic criterias that are based on sustainable development. Each of these criterias has some subcriterias which we have obtained their importance by FAHP then routes were classified by GRA. One of the advantages of this project is using subjective and objective datas to order alternatives simultaneously. Results show that in spite of the first expectation, the best route is not necessarily the shortest one and by considering sustainable development criterias among these recommended routes the best one is Eghlid to Sadeh. Keyword: Sustainable development, Fuzzy Analytical Hierarchy Process(AHP), Grey Relation Analysis(GRA), Optimum Route.