In order to effectively realize the energy saving and emission reduction of construction industry and realize carbon peak and carbon neutrality, the accounting method of construction carbon emission was studied. Based on the life cycle theory, the building carbon calculation model at the urban level was established, and the carbon emissions of residential and non-residential buildings in Shanghai were calculated. By comparing the carbon emissions of residential and non-residential buildings, the carbon emission trend of buildings in Shanghai was studied. The research results show that the carbon emissions in the construction field in Shanghai have maintained a growth trend from 2010 to 2020, and the production stage of building materials and the operation stage of the building are the two stages that have the largest contribution to the overall carbon emissions of buildings. From the perspective of the proportion of carbon emissions of different building materials, the carbon emissions of steel are the highest in the carbon emissions of building materials, accounting for more than 50%, followed by cement and aluminum. In terms of building a carbon reduction path, the corresponding emission reduction counter measures are put forward combining with the carbon emission accounting results of each life cycle stage of the building.