Cities consume a considerable amount of fusil fuels energy and as a result emit carbon dioxide significantly. Developing a carbon emission assessment system for low carbon urban planning has become an important approach for reducing carbon emissions and achieving low carbon eco-city development goals. Analysis of LCC (Low Carbon City) indices of the city of Isfahan and its comparison, via TOPSIS algorithm, with the cities of Beijing and Stockholm shows that this city is not in a good position regarding its ranking among the industrial low-carbon cities. Excessive use of fossil fuels and not utilizing renewable energies are the main reasons for the low rank of Isfahan among the other cities in the world. Dealing with the challenges ahead of developing of an Iranian low carbon Eco-city discussed in this paper is critical. However, the results of this study indicate that the occurrence of some of these challenges is inevitable in the process of achieving a low carbon and sustainable urban development. Moreover, a basic understanding of LCC not only minimizes energy use and natural resources but also contributes to social development, environmental protection and improving the quality of life in Isfahan.