[Abstract] Northeast Asia has suffered from high concentration of particulate matter, prompting nations to actively implement emission reduction policies. Emission reduction not only decreases the concentration of air pollutants in the emission source area but also influences the long-range transport of these pollutants to downwind areas. This study analyzed the changes in behavior and chemical transformation processes of long-range transport pollutants resulting from the recent reduction in Chinese emissions and assessed their impact on the Korean Peninsula. Analyzing ground measurement data from the KORUS-AQ campaign in 2016 to the SIJAQ campaign in 2022 over a seven-year period, we found a clear decreasing trend of PM2.5 and SO2 in both the upwind areas (specifically, the Beijing-Tianjin-Hebei area of China) and the downwind areas (including Seoul on the Korean Peninsula) as well as in the background area in the Yellow Sea. We also analyzed aircraft measurement data and chemical transport model results from May to June in 2016 and 2022, spanning the two campaigns, to assess the impact of reduced pollutants in major emission regions in China on long-range transport. Our aircraft measurement data indicated a decrease in the levels of NO2 and SO2, which are precursor gases for major inorganic aerosols such as sulfate and nitrate. This decrease was particularly pronounced at altitudes ranging from 500 m to 1 km. Furthermore, ground measurement data from the western coast of South Korea and Seoul indicated lower levels of both particulate and gaseous air pollutants in 2022 compared to 2016, which was consistent with the model results. Notably, the model-calculated ratio of secondary aerosol formation over the Yellow Sea exhibited an average reduction of over 5% in 2022 compared to 2016. Thus, our findings suggest that the recent reduction in Chinese emissions has contributed to both a decrease in the long-range transport of aerosols formed in China and a reduction in the chemical transformation, including gas-to-particle conversion, over the Yellow Sea. Consequently, this could ultimately lead to an improvement in air quality on the Korean Peninsula.