Abstract: With the continuous improvement of air quality in Kunming since 2015,however,the near-surface concentration of O₃ is on the rise. O₃ has exceeded PM to become the main negative factor affecting the excellent rate of air quality. Based on the hourly concentrations of near-surface O₃ over the past 5 years,the annual,diurnal and seasonal changes were examined. The results discovered that the near-surface O₃ has been increasing slowly and continuously year by year. The hourly O₃ was highest in spring,and lowest in autumn. Peak interval of O₃ was longer in spring daytime than other seasons,and nighttime concentration was also higher. The near-surface O₃ in Kunming reached a maximum value at approximately 2∶ 00 to 5∶ 00 p. m. daily and a minimum value at approximately 8∶ 00 a. m. This paper explained the impact of the topographic factor and the meteorological factor on the near-surface O₃. There might be a long distance external input in the horizontal direction and vertical transmission channels in the atmosphere. Finally,a series of control countermeasures with O₃ for Kunming was proposed.