Thermal power generation is the main electricity source of China, but also contributes the largest share of air pollutants in the country. Because of China's considerable efforts in pollution control, one measure of the most important source of air pollution net SO2 emission intensity (NSEI) of thermal power generation has dropped significantly since 2006. Understanding the reasons behind the decline could help further explore the solution-space for deeper mitigation targets. This study combines multiplicative LMDI with attribution analysis to decompose the decline in national NSEI into four factors (i.e. SO2 treatment or end-of-pipe approaches; SO2 emission factor of coal and coal intensity, which both account for cleaner production measures; and geographical structure effects) for 30 regions. Our results show that end-of-pipe technologies remained the primary way to control air pollution in China. In addition, cleaner production efforts contributed to SO2 mitigation. Attribution results at the province level show that northern provinces increased their efforts in SO2 treatment and reducing coal intensity, while southern provinces have done more on reducing the SO2 intensity of coal. Provinces were classified into four categories (i.e. leading regions, end-of-pipe dependent regions, process-dependent regions and lagging regions) according to their performance in terms of end-of-pipe treatment and cleaner production, to help them choose targeted policy methods.