Abstract: O₃ pollution has become one of the major environmental problems and a new challenge for air pollution prevention and control in China. However, seasonal variation of O₃ concentration and its correlation with meteorological factors are still unclear due to the lack of monitoring data and knowledge. Based on the long-term monitoring data set from March 1^st, 2014 to February 28^th, 2021, seasonal variation of O₃ in the ‘2+26’ cities in the Beijing-Tianjin-Hebei Region and surrounding areas were analyzed by using partial correlation analysis methods. The results showed that: (1) The average annual increase of O₃ concentration in the whole region was 3.82 μg/(m³·a) during 2014-2020, showing an obvious upward trend in the first stage and a slight downward trend in recently years. The seasonal change characteristics of O₃ concentration were summer > spring > autumn > winter. (2) From 2014 to 2020, the days of mild pollution accounted for the largest proportion of O₃ pollution days and had an obvious increase in summer. (3) The negative correlation between O₃ and CO and NO₂ increased in summer and winter, while the relationship between O₃ and SO₂ concentration changed from a significant negative correlation in spring, summer and autumn to a significant positive correlation in summer and winter. (4) There was a significant positive correlation between O₃ concentration and daily average temperature in spring and autumn, a negative correlation with relative humidity in summer and winter. These findings will help to understand the underlying reasons for O₃ variation and provide important information to guide targeted policy response to O₃ pollution.