Promoting the Beh and Road Initiative may do good to regional economic growth，but it may also increase carbon dioxied emissions. In order to prevet the same siut anion of carbon emssion increase after China's entry of WTO and to prevent the developed couWries' imposing" low carbon trap" on China，it is an important to focus on both the economic growth and carbon reduction for the implement ation of the Beh and Road Initiative. Based on the synergy Theory，this paper builds a synergy-degree model of a complex system that centers on both economic growth and carbon emissions reduction and calculates the synergy-degree of China. Furthermore，on the basis of the grey theory，the paper explores the key factors that have impact on the synergy-degree of China.The study shows that the synergy-degree of economic growth and carbon emissions reduction of China goes up after dropping from 2000 to 2013. Although the Synergy-degree is very low，the overall trend becomes beUer. Energy intensity and non-fossil energy radio are the fop two factors that have effect on the collaborative development of economic growth and carbon emissions reduction in China. Based on this，the paper puts forward some suggestions to build a low carbon Beh and Road Initiative.