Handan was one of the most polluted cities in China since 2013 and has become the top one PM2.5 polluted city in 2017. In this research, we observed coarse particulate matter (PM10), fine particulate matter (PM2.5), submicron particulate matter (PM1), and chemical composition of PM2.5 from November 16, 2015 to March 14, 2016 in Handan. During the observation period, hourly concentrations of PM10, PM2.5, and PM1 peaked at 1070.1, 864.4, and 519.5 µg m–3, respectively. Severe pollution occurred in a large fraction of days in the heating season characterized by frequent and long-lasting pollution episodes. A large fraction of the transport trajectories during nine typical episodes during that period in Handan were from the northwest. Water-soluble ions (sulfate, nitrate and ammonium) of PM2.5 accounted for the largest proportion in all pollution levels. The highest proportion of SIA occurred in a heavily polluted episode that was as high as 50.0% (sulfate 18.8%, nitrate 18.7%, and ammonium 12.5%). The sulfate and ammonium in PM2.5 increased gradually while nitrate in PM2.5 decreased from the clean level to the heavily polluted level. The fraction of SOA and OM to PM2.5 decreased as the pollution level increased, indicating a weakening of photochemical reactions. POA in PM2.5 increased with the aggravation of haze, and the heterogeneous chemistry was enhanced with the aggravation of pollution. Liquid reactions were important in the formation of sulfate in the pollution and non-pollution stages. Liquid reactions of NO2 would be enhanced in the pollution stage during the heating season in Handan.