China National Experimental Sustainable Communities(CNSCS) are of great importance as the experimental and demonstration bases regarding the sustainable development strategy carried in China.Evaluating the sustainable development level is one of the key topics of CNSCs study.Based on the concept of emergy,we established an assessment index system considering emergy total,emergy intensive degree and emergy efficiency,and proposed three indices including emergy sustainable index(ESI),sustainable development index(SDI),and urban eco-efficiency index(UEI).Taking the CNSCS of Yulin City as an example,we evaluated the sustainable development level using the established approach.The results showed that,from 2000 to 2008,the ESI was much larger than 10 but kept reducing continually,indicating that the economic development level of Yulin City was still underdeveloped.The SDI decreased year by year,implying reducing social and economic benefits under the environment pressure.The UEI also decreased gradually,suggesting that the self-organizing capacity,the development potential and the recycling capacity of Yulin City still needed to be improved.Emergy analysis method provides a new ways to assess the sustainability of CNSCS,which generates more objective assessing results.The method can be used to evaluate and compare the sustainable level of CNSCS of different levels and different sizes by eliminating the obstacles induced by the differences of research objects.It has a direct significance for identifying the development problems and optimizing development strategies of the CNSCS.