According to the observational data between 2014 and 2019 from China National Environmental Monitoring Center，the spatial and temporal characteristics of ozone pollution in different seasons over the Yangtze River Delta are analyzed． Summer has the most serious ozone pollution in the region，followed by spring． However，the month with the most serious ozone pollution is May in spring， which is also the season with the most obvious increasing trend of ozone pollution in recent years． The contribution of biogenic emissions to ozone pollution is further explored using the WRF-CMAQ model． The three months with the largest contribution of biogenic emissions are in summer． The average MDA8 (the maximum daily 8-hour average ozone)concentration in summer is 8. 0 ppb，and the monthly average MDA8 concentration is the highest (10. 4 ppb)in July． Especially in the northeast of Zhejiang Province， the ozone contributed by biogenic emissions accounts for 20% of the total ozone production． The seasonal average concentration of MDA8 from biogenic emissions is about 3. 0 ppb in spring and autumn and the influence of biogenic emissions is the least in winter． Combing with the latest air quality guideline in 2021 from the World Health Organization (WHO)which stresses long-term ozone pollution in the warm season，this study elucidates the importance of future ozone research for multiple seasons，not just focusing on summer． Moreover，the effect of biogenic emissions on ozone may become more important under the reduction of anthropogenic emissions in the future．