The data of 30 provinces，region and cities in China from 2007 to 2019 are selected，by constructing a quasi-natural experiment with carbon emission trading policy, and using the propensity score matching-double difference model to analyze the carbon emission reduction effect of the carbon emission trading pilot on the region. The study found that carbon emissions trading reduced carbon emissions in the pilot area. After the intermediary effect test, it is found that carbon emission rights trading promotes carbon emission reduction by causing the industrial structure upgrade and energy consumption structure optimization in the pilot area, accelerating the adjustment and upgrading of the industrial structure in the pilot area, increasing the proportion of clean and low-carbon energy consumption, reducing consumption of fossil energy such as coal. Through the analysis of synergistic emission reduction effect, it is found that carbon emission rights trading has played a role in synergistic emission reduction, reducing the emissions of other pollutants such as sulfur dioxide.