Abstract: In order to explore the causes of ozone pollution in Hengshui City during spring and summer,the meteorological conditions and potential source areas of an ozone pollution processepisode in Hengshui in June 2022 were analyzed by using real-time monitoring data and ERA5 reanalysis data.The results showed that:the relative humidity is less than below 50 %,the daily maximumpeak hourly temperatures is above 30 ℃,the wind speed is lows (less than below 4 m/s) and prevailing easterly to southeasterly winds the dominant wind direction is east-southeasterly wind,were significant contributing which is an important factors causing thise ozone pollution event in Hengshui City.The potential source areas of ozone in this pollution processepisode mainly involved the cities includingof Cangzhou,Xingtai,Puyang,Dezhou,Liaocheng,Heze,Jining,Tianjin and Tangshan,which are theshould be key cities for the joint prevention and control of ozone in Hengshui City.The meteorological conditions that favored this severe pollution event included low-level wind speeds in the lower atmosphere and stable weather situationpatterns in the precedingearly periodstage,the obvious sinking movement throughout the atmospheric columnof the whole layer on the day of severe pollution,frequent wind direction shifts with low wind speeds in the lower atmospherethe low-level wind speed and frequent wind direction conversion,andas well as the meteorological conditions of high temperatures and low humidity are all conducive to the occurrence of this heavy pollution weather.The ventilation threshold of this ozone pollution process in Hengshui City was approximatelyabout 10×10³ m²/s,indicating generally unfavorable meteorological conditions for pollution dispersionand the overall meteorological diffusion conditions are unfavorable.