Carbon footprint is the total amount of CO2 emissions by particular product or service system in it full life cycle, or, it is the total amount of direct and indirect CO2 emissions by activity principals. There are significant differences of provincial total carbon footprint result from the different energy efficiency, final demand and input-output relationship of intermediate products. Based on the Structure Decomposition Analysis and input-output model, the differences of carbon footprint between Beijing and Tianjin are analyzed in this paper. The results show that the total carbon footprint is higher in Beijing than that in Tianjin. The effect of carbon emission intensity on carbon footprint in Beijing is lower than Tianjin by 0.008 billion tons CO2; according to the complicated relationship between industries in Beijing, there is 0.029 billion tons CO2 more the carbon footprint than Tianjin, The demand scale and structure is higher than Tianjin, So in the factors of final requirements on carbon footprint, the carbon footprint of Beijing is higher than Tianjin by 0.058 billion tons CO2.