In recent years,ozone pollution in the summer has increasingly become problem a significant concern affecting air quality and environment in eastern China.This study aims to quantitatively evaluate the impact of reducing ozone precursor emissions on ozone pollution.Using the ozone pollution episode in eastern China from June 19 to 30,2021,as a case study,we use CMAQ-DDM air quality model and satellite remote sensing inversion algorithm to analyze ozone concentration sensitivity to anthropogenic precursor emissions in the eastern region.Different reduction scenarios for ozone precursors are simulated by setting different reduction ratios.The findings reveal the following:1) From June 19 to 30,2021,an extended regional ozone pollution event occurred in eastern China,with most cities experiencing slight to moderate pollution levels;2) Throughout the pollution period,the eastern region was predominantly influenced by VOC control or a combination of VOC and NO_x control.Model simulations and satellite inversions exhibited good agreement.In the early stage of the pollution event (June 19-25),the eastern region was highly sensitive to VOCs,while in the latter stage (June 26—30),it transitioned into an area where coordinated control of VOCs and NO_x was crucial,especially in Henan,Anhui,and Jiangsu;3) When applying the same emission reduction ratio (VOCs∶NO_x=2∶1),larger emissions reductions led to greater reductions in ozone levels.Increasing the VOC reduction ratio from 20％ to 40％ resulted in an ozone concentration reduction ranging from 1.7％ to 3.6％.Phased emission reduction strategies outperformed single-period reduction plans,achieving a 0.1％ increase in the ozone improvement rate.Reducing only elevated NO_x sources did not significantly decrease ozone concentrations.