Based on the indicators of economic value and environmental impact established by emergy and material flow method, the relationship between economic development and environmental quality was analyzed with the aspects of the features of environment Kuznets curve(EKC), eco-efficiency and the "decoupling". The results showed that:the characteristics of "inverted U" type was appearent between economic development and environmental quality, the turning point of EKC will occur before 2015, then the economic value and environmental impact will increase 8.83 and 4.38 times over 2009, respectively; Eco-efficiency increased 4.55 times in the last 11 years and is based on increasing ecological pressure; The decoupling phenomenon was characterized with alternative weak decoupling and expansion re-link and economic development was characterized with obvious weak sustainability, compared to waste discharge, resources input has a more significant role in promoting ecological pressure. Thus, it is the only ways for Yulin City to change traditional way of economic growth and develope circular economy to promote Yulin City to meet the whole social material needs, and at the same time, to achieve the coordinated development of economic development and population, resources, environment.