Abstract: Based on surface ozone (O₃) mass concentrations and meteorological data in Jinan and Qingdao during 2014 to 2021, the variation characteristics of daily maximum 8-hour moving averages of ozone concentrations (O₃-8h concentrations) and its relationship with meteorological factors were studied. Backward trajectories were also combined with O₃ concentrations for trajectories clustering and potential source regions of O₃ analysis. The results showed that level of O₃ pollution in Jinan was generally higher than that in Qingdao. The O₃ pollution episodes were observed from April to October. The annual trend of 90^th percentile of O₃-8h concentrations (O₃-8h 90^th concentrations ) in Jinan generally showed an upward trend and then a downward trend from 2014 to 2021. Moreover, the peak value of annual O₃-8h 90^th concentrations in Jinan was observed in 2019. The annual O₃-8h 90^th concentrations of Qingdao in 2019 and 2017 showed a little higher than those in other years. The annual O₃-8h 90^th concentrations of Qingdao in the other years showed little difference. The monthly variations of O₃-8h 90^th concentrations in Jinan were more significant, with a unimodal distribution. However, the monthly variations of O₃-8h 90^th concentrations in Qingdao had a bimodal distribution, due to the influence of summer rainy season and clean maritime air mass dilution. The high O₃ concentrations were more easily caused by unfavorable weather conditions, such as high temperature, low relative humidity and light wind. Compared with that in Qingdao, O₃-8h concentrations in Jinan had a closer correlation with meteorological factors, especially with mean air temperature from 8:00 to 17:00 (T_8-17). When T_8-17 was greater than 15 ℃, for every 1 ℃ increase in T_8-17, O₃-8h concentrations in Jinan was increased by 6.1 μg/m³. O₃-8h concentrations in Qingdao was fluctuated increased with the increase of T_8-17. However, for every 1 ℃ increase in T_8-17, O₃-8h concentrations in Qingdao was only increased by 1.5 μg/m³. The O₃ concentrations in Jinan were much higher, with mean of (113±51) and (109±57) μg/m³, respectively, when the airflow came from southwesterly and south-southeasterly areas, which was the central and eastern junction of Jiangsu-Anhui-Shandong-Henan region. The O₃ concentration in Qingdao was (106±45) μg/m³, together with the southwesterly airflow beginning at the inland regions. The main potential source regions of O₃ in Jinan and Qingdao shared a same region, mainly located at the central and eastern of junction Jiangsu-Anhui-Shandong-Henan region and the central Shandong region. Based on all the above research results, the O₃ pollution in Jinan and Qingdao were mainly driven by local emission. The regions of coordinated inter-regional O₃ prevention and control for Jinan and Qingdao should focus on the central and eastern of junction Jiangsu-Anhui-Shandong-Henan region and the central Shandong region.