The embodied stage of city buildings has the characteristics of concentrated emission time and large emissions, which involves large volumes, many processes and complex material types, and there are few studies on carbon emission examples in the embodied stage. The team first clarified the calculation method and basic process, then investigated a large number of projects to propose a carbon emission accounting method that is different from the traditional calculation model, and finally used the two models to calculate the carbon emissions of multiple buildings in four projects. The results show that the average error between the new model and the traditional model is 3.5%, the average carbon emission intensity of the selected case is 400 kg/m2, and the carbon emission of civil engineering accounts for more than 75% of the embodied stage, which is the most important type of project. All kinds of steel and commercial concrete account for 80–90% of carbon emissions in the embodied stage, which is the most important material type. It is of great significance to select green building materials and improve the building assembly rate to reduce carbon emissions in the embodied stage.