Abstract: The carbon emission of three industries with 15 main energy from 2000—2009 in Tianjin was calculated based on 2006 IPCC Guidelines for National Greenhouse Gas Inventories, which was decomposed into carbon emission factor, energy structure, energy intensity, economic structure, and economic development with LMDI. It showed that in 2001—2009, economic development and carbon emission factor promoted carbon emission; energy intensity, energy structure and economic structure inhibited carbon emission increase, among which energy intensity was the most important factor. To confirm the characteristic of energy intensity change, this paper decomposed the energy intensity into structure portion and efficiency portion. It showed that the efficiency improvement of Tianjin contributed to energy intensity decrease in 1999—2009, and the increase of the energy service efficiency of the third industry played the most important role.