Energy efficiency is one important index of a regional economic and social sustainable development strategy. To find some original factors influenced on the energy efficiency, we used energy data concerned during 1996-2008 in China and calculated the efficiency data in Laspeyres Decomposition, then analyzed the factors' influence values and energy efficiency's developing trend, at last, put forward the strategic advice. The data showed that energy intensity has declined from 1996 to 2008, and energy intensity change was mainly affected by technological progress factors. Except for 2002 to 2003, the energy intensity was declining in rest periods, and the factor of technological progress and the factor of the drop in life consumption have been playing positive roles to the decrease in the energy intensity, while the unreasonable industrial structure change had a negative effect on the decrease in the energy intensity.