With the rapid development of urbanization, many housing constructions are being built in southwest China, which resulted in tremendous use of building materials, posing a potential threat to the environment. In order to formulate policies for low-carbon, green and sustainable development of buildings, it is necessary to explore the driving factors behind it. This research firstly calculates the embodied carbon emissions of buildings in Southwest China from 2001 to 2020, uses Tapio decoupling to examine the decoupling relationship between economic development and embodied carbon emissions and adopts the Logarithmic Mean Divisia Index decomposition analysis method to investigate the contribution of factors such as technological level, economic structure, per capita Gross Domestic Product and population density to the embodied carbon emissions of buildings. The research shows that: (1) The total embodied carbon emissions of building materials in Southwest China increased by 218.62%, of steel and cement contributed the most of carbon emissions. (2) In the past 20 years, the degree of decoupling in Southwest China has fluctuated greatly. During the "13th Five-Year Plan" period (2016-2020), the provinces and cities in southwest China have an enormous degree of decoupling: Yunnan (- 0.141) > Guizhou (- 0.013) > Chongqing (0.047) > Tibet (0.120) > Sichuan (0.256). (3) The technological level is the first leading factor in the reduction in the embodied carbon emissions of buildings in southwest China, and the per capita Gross Domestic Product is the key factor to promote the growth of embodied carbon emissions. These findings could serve as a foundation for Southwest China's government to develop low-carbon building policies. [GRAPHICS] .