Eco-efficiency of carbon emissions derived from energy consumption is a key issue in the field of ecological economic research, as well as a hot topic that has attracted government decision-making departments and has caught the attention of industry professionals and the public. Based on the concept of energy metabolic analysis (EMA), the ecological efficiency measurement model of carbon emissions from city energy consumption was established, and the energy consumption and carbon emissions of Nanchang from 2000 to 2013 were calculated and analyzed. The eco-efficiency of carbon emissions from energy consumption in Nanchang was also analyzed. The results showed that:(1) In 2000-2013, the energy consumption and carbon emissions of Nanchang had been increasing as an N-shape curve on the whole, mainly exhibiting three stages, including rapid growth, short-term decline, and steady growth. Coal was the main source of the city's energy consumption and carbon emissions, which would be difficult to change in the short term; (2) The energy consumption efficiency and carbon emission efficiency of Nanchang were improving on the whole; (3) The comprehensive ecological efficiency of energy consumption in Nanchang did not greatly improve, suggesting the ongoing need to increase the intensity of energy-saving emission reduction efforts, and to optimize the energy consumption structure.