Abstract: This paper calculates the carbon emissions from urban passenger transportation sector in Beijing and Shanghai from 2000 to 2012, and then discusses the effects of population, per capita economic activity, transportation intensity, transportation mode share, vehicle-use intensity and emission coefficient on carbon emissions based on LMDI decomposition analysis. Results shows that:(1) carbon emissions due to urban traffic has increased rapidly both in Beijing and Shanghai, and the emissions in Beijing are far larger than Shanghai;(2) per capita disposable income, vehicle-use intensity, and population effect are found to be the main drivers that increase household daily travel carbon emissions;(3)transportation intensity and transportation mode share have significant effects on the reduction of carbon emissions;(4)emission coefficient plays the opposite effect on carbon emissions in Beijing and Shanghai.