Abstract: Air quality is affected by the emission of pollutant sources and meteorological conditions. In order to quantitatively evaluate the effects of meteorological conditions on air quality, a stable weather index is established using 872 groups of meteorological and environmental data in the heating seasons of 2014-2016 in Shenyang, which involved different physical parameters such as relative humidity, wind speed, inversion temperature intensity, and mixing boundary layer height, and the relationship between the index and air quality was analyzed in this study. The threshold of stable weather index (= 9.1) can identify two major causes of severe air pollution events in Shenyang. One reason is stable weather situation, and the other is pollutant transport from other regions under unstable weather conditions. The stable weather index is proved as a good indicator for air quality through analyzing the relationship between it and PM2.5 concentrations at different pollution levels. On the whole, when the stable weather index is larger than 10.4, air pollution event usually occur. With the increase in the stable weather index, air pollution tends to be heavier. Therefore, the stable weather index can be used to predict air quality from the view of meteorology.