With the economic development in Shanghai, a lot of energy has been consumed in the building industry, and is accompanied by a great amount of carbon emissions. Based on the data of energy consumption in the two stages of the building materials production and construction process in Shanghai, a calculation model of CO2 emissions was created, total CO2 emissions have been evaluated during recent ten years, and CO2 emissions influencing factors was identified in each stage. The research results show that CO2 emissions in the stage of building materials production, account for more than 90% of total CO2 emissions, mainly traced from cement, iron and steel industry, and have greater potential for energy conservation and emissions reduction.