Based on the mass concentrations of fine particulate matter (PM2.5) in Rongchang District in winter from 2016 to 2018, surface meteorological observation data, L-band radar sounding data, ERA-Interim reanalysis data and GDAS (global data assimilation system) data, combined with the HYSPILT model, the meteorological influencing factors and regional transmission of PM2.5 in winter were analyzed. The results are as follows: (1) The frequency of PM2.5 mass concentration exceeding 75 μg·m-3 was as high as 56.3% in winter in Rongchang District from 2016 to 2018, but the air quality became better year by year. The diurnal variation of the PM2.5 mass concentration in winter had two peak values, appearing at 12:00 and 23:00. (2) PM2.5 pollution was mainly influenced by precipitation, temperature inversion and low-level wind speed. The obvious temperature inversion stratification near 925 hPa and 700-600 hPa in the surface layer, northwesterly or flat westerly airflow on 500 hPa, and weak northeast wind below 850 hPa, were unfavorable to PM2.5 pollutant diffusion and prone to occur severe pollution weather. The precipitation more than 2.0 mm had a clear clearance effect on PM2.5, the scavenging ability increased with the increase of precipitation level. The precipitation less than 1.0 mm had negative effect in the removal of PM2.5. Unfavourable diffusion condition  and hygroscopic growth of particulate matter led PM2.5 mass concentration to increase during micro precipitation period. (3) The PM2.5 pollution situation was mainly affected by the regional transportion between Chengdu and Chongqing urban agglomerations within about 300 km from the northwest and northeast of Rongchang District. The transmission of particulate pollutants in the outer domain was an important cause of PM2.5 pollution in winter in Rongchang District.