With the rapid development of global economy, environmental problems have become more and more prominent. In 2007, China’s CO2 carbon emission has surpassed the United States and become the world’s largest CO2 emitter. Hence in the global energy saving and emission reduction targets,China has more energy saving and emission reduction task than other countries. This paper utilized two-stage LMDI decomposition to decompose China’s carbon emission intensity. In the first stage, LMDI model was applied to decompose carbon emission intensity. Decomposition result shows that the reduction of carbon emission intensity in China is mainly influenced by energy intensity and energy structure. Energy intensity contributed more than 90% on changes of carbon emission intensity, while the impact of energy structure is relatively small. In the second stage LMDI decomposition of energy intensity was conducted, which is the main factor influencing changes of carbon emission intensity. Decomposition result shows that the reduction of energy intensity in China mainly resulted from industrial structure and energy efficiency during 1991-2011. Finally,Johansen Co-integration test was employed to test the long-term co-integration relationship between variables. The result suggests that there has been a long-term equilibrium and stable relationship among carbon emission intensity and energy structure, technological progress, industrial structure. Based on the above analysis, three suggestions for energy saving and emission reduction are provided.