With the implementation of a series of air pollution reduction policies, aerosol pollution in China has been effectively controlled. However, in recent years, ozone (O3) is gradually becoming the most critical air pollutant in China. High O3 concentrations damage ecosystems, reduce crop yields, and harm human health. Therefore, it is great significance to reveal the factors that influence the variation in O3 concentrations in China and understand the reasons behind it. El Niño–Southern Oscillation is the strongest signal of interannual variation in the ocean, and has significant impacts on global weather conditions and atmospheric circulation. Previous studies have focused on the influence of El Niño on aerosol concentrations in China. However, the effect on summertime near-surface O3 in China has been insufficiently investigated.