Against the background of global climate change，the development of a low-carbon economy has become a consensus of decision makers at all levels. Energy-saving & emission reduction，as well as promoting low-carbon development is not only a solution to global warming，but also an important means of practicing scientific development. As an important platform of implementing energy-saving & emission reduction as well as developing a low-carbon economy，low-carbon city building will lead the new trend of urban development in the future. This article firstly describes the macro context and the progress of the work of China’s energy-saving & emission reduction and low-carbon city building，then analyzes the existing difficulties，and finally puts forward countermeasures and suggestions to promote China’s energy-saving & emission reduction as well as low-carbon city building.