With the increase of population and economic development，the environmental quality of Erhai Lake Basin is gradually declining. In order to assess the present sustainability of Erhai Lake Basin，an emergy-based framework was used. It can help to understand the relationship between natural ecosystem and socioeconomic system，so that the key factors which influence the sustainable development of Erhai Lake Basin can be found. Results show that the whole basin is far away from sustainable development in 2014. The main contributors are cement industry and chemical fertilizers. Policy insights for improving the overall sustainability of Erhai Lake Basin are proposed，including adjusting industrial structure and promoting circular economy，facilitating green agriculture，improving water efficiency and increasing renewable energy use.