Abstract: Based on historical air pollution index data from China Air Quality Online Monitoring and Analysis Platform and conventional MICAPS upper-air and surface observation data from 2015 to 2021, the characteristics of heavy pollution weather in Dazhou were analyzed, including seasonal variations, changes in concentrations of major pollutants, and meteorological conditions. The results indicate that: (1) Heavy pollution days in Dazhou exclusively occurred in winter, with both the number of heavy pollution days and their proportion among total pollution days showing a declining trend. Since 2018, the number of heavy pollution days in Dazhou decreased significantly, indicating a gradual alleviation of air pollution over the years. (2) The primary pollutants during heavy pollution weather in Dazhou were PM_2.5, CO, SO₂, NO₂, and O₃. None of the four major pollutants exceeded daily concentration standards. (3) The 500 hPa circulation patterns associated with heavy pollution weather in Dazhou can be classified into three types: westerly flow pattern, northwesterly flow pattern, and pre-trough southwesterly flow pattern. The surface weather patterns can be divided into cold high-pressure bottom type, uniform pressure field type, and rear of cold high-pressure type. (4) During heavy pollution events in Dazhou, temperature inversions of varying intensities were present in the middle and lower layers of the atmosphere, accompanied by a stratification characterized by "dry air above and moist air below". Surface wind speeds were predominantly calm (Force 1), with calm winds being the second most frequent.