Abstract: The changes of AQI of each national air quality monitoring site of Kunming in 2019 were analyzed. It was found that the general air quality in Kunming was good. The relative most serious air pollution happened in spring. The autumn had the least pollution all the year round. No obvious weekend effect was found. The main pollutants that caused the air pollution in Kunming were O₃-8h, PM₁₀, and PM_2.5.