Due to the increasing global concerns about the increasing social instability in agricultural development projects in rural areas, the main purpose of this study was to evaluate the economic, social and environmental impacts of Tangab dam and irrigation network in Firuzabad. Accordingly, economic criteria and multi-criteria analysis approach was applied for determining non-economic Impacts of the dam. The results demonstrated that for discount rate of 12%, the Net Present Value is 4. 1×108 billion rails, Internal Rate of Return of the project is 25. 42. In addition, Sensitivity analysis for discount rate various, changing benefits and cost and different project age revealed that the project was economically reasonable. Furthermore, the multi-criteria analysis demonstrated that the most significant positive impacts of the project were: improving the agriculture of the region, increasing the level of groundwater, flood control, improving the climate of the region, increasing value of the area, tourism conditions improvement, and developing the water sports. Also, the most important negative impacts of the project were caused by: the dam construction, embankment and excavation, digging tunnels and building new roads, cutting down trees and environmental damage, land acquisition and displacement and resettlement of people. In general, multi-criteria analysis indicated that the positive impacts of the Tangab dam project were more significant than the negative impacts.