A heavy air pollution process in Beijing was observed from March 29 to April 10, 2018, and its pollution characteristics and optical characteristics were analyzed by using air quality monitoring data and the observation data of AERONET Beijing station. Combined with HYSPLIT airflow backward track mode, the temporal and spatial transport characteristics of atmospheric particles during this heavy pollution were comprehensively studied. The results show that, the heavy pollution process was dominated by fine mode aerosols with weak absorption, and the PM2.5 concentration and aerosol optical characteristics were significantly affected by the meteorological element during the pollution process. The results also show that the results from AERONET are in good agreement with those from the ground air monitoring stations, which indicates that AERONET results can be adapted to the study of aerosol optical characteristics in heavy air pollution process.