The ambient PM₁ levels during late autumn and winter season in Qingdao were monitored for two consecutive years (November 1st to next January 31st of 2017 and 2018).The carbon components of PM₁,and other atmospheric pollutants of PM₁₀,PM_2.5,SO₂,and NO₂,as well as correlated meteorological conditions,were used to trace the sources of ambient PM₁ in Qingdao.The results showed that the average daily concentrations of PM₁ were 40.58±25.98 μg/m³ and 42.55±25.05 μg/m³ for the two observation periods,which increased to 84.71±16.70 μg/m³ and 81.52±18.39 μg/m³ during haze episodes.The mass concentrations of OC and EC in PM₁ in haze days were 13.67±3.95 μg/m³ (16.48±6.34 μg/m³),3.95±1.02 μg/m³ (3.34±1.16 μg/m³) for year 2017(2018),respectively.While the SOC mass concentrations in haze days were 1.28 and 2.15 times of those in non-haze days for year of 2017 and 2018,suggesting the strong potential of secondary transformation of organic carbon during haze episodes.Three factors were apportioned through principal component analysis of carbon-containing components.Factor 1 has the largest explanatory variables,which were 58.98% and 67.14% for 2017 and 2018,indicating the carbon-containing components of PM₁ were mainly from sources of biomass combustion,coal burning,road dust,and gasoline vehicle exhaust.The backward airflow trajectory analysis showed that the air masses were mostly originated in Inner Mongolia and passed through Hebei,Tianjin,or other cities of Shandong and finally arrived at Qingdao.