To investigate the calculating method of eco-efficiency, a calculation formula, which combined with emergy analysis and material flow analysis, was established and then it was applied to Jilin Province. The main results could be summarized as follows: ① In the past 17 years, eco-efficiency has increased by 2.9 times. ② The improvement of eco-efficiency makes environmental pressure decrease by 205.62% and its average contribution to economic growth is 63.7%. ③ Population growth is not the main cause for increasing environmental pressure. The influence of material input on environmental pressure is more obvious than that of waste discharge, but its decoupling index is lower. ④ After 2000, with the slow increase of eco-efficiency, its inhibitory effect on environmental pressure and promoting effect on economic growth are both decreasing. Furthermore, the decoupling indexes of most indicators are shrinking. The unsustainable factors are enhancing in Jilin Province. The result could be helpful to deepen the calculating method of eco-efficiency in theory and reflect the limitation of environmental policy in practice. Also, the result could benefit the sustainable development of Jilin Province to some extent.