To accurately calculate the actual CO 2 emissions of China's domestic construction industry (CDC) under the influence of international trade factors, an improved import proportion method (IIPM) was suggested in this paper based on the non-competitive input-output (NC-IO) table in 2017. The NC-IO table of 10 years from 2010 to 2019 was complemented in combination with the Row arrange series (RAS) method, and the CO 2 emissions of the CDC in the 10 years were calculated by the input-output (I-O) method. The results reveal that CO 2 emissions of the CDC keep increasing, with an annual increase of 6.57%, and the proportion thereof to domestic CO 2 emissions has increased from 17.00% to 22.52%, although the carbon intensity has decreased by 39.6%. On this basis, by Structural decomposition analysis (SDA) model analysis, the change in CO 2 emission influencing factors in the past 10 years was analyzed from the perspective of CO 2 emissions factor, industrial structure, and domestic final demand. The results indicate that the IIPM is more accurate and the calculation is more reliable based on 5 indicators. Additionally, the optimization of the industrial structure after 2015 has had a significant dampening effect, and the final demand has played an absolute leading role in improving CO 2 emissions. From the perspective of final demand, the current emission reduction measures in the CDC, including prefabricated buildings, are not satisfactorily effective, and more efforts need to be made in emission reduction. Furthermore, the contradiction between the growth of final demand and the demand for CO 2 emissions reduction is prominent.