In order to understand the characteristics, sources and processes of non-refractory submicron particles (NR-PM 1 ), an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed to acquire observational data during the spring (April 1 to 30) in Beijing, China, in 2012. Based on PM 10 , PM 2.5 and NR-PM 1 mass concentrations observation, satellite images and the back trajectory analysis, one haze and dust storm episodes were recorded during the campaign, in addition, one clean episodes was also added to the comparison as a reference. The NR-PM 1 mass concentration was 97 µg m -3 during the haze episodes, while it was approximately 12 times and 1.7 times that on the clean and dust episodes, respectively. In addition, the secondary inorganic aerosol (sulfate, nitrate and ammonium) contributed the largest fraction of NR-PM 1 (69%) during the haze episodes. The dust storms originated from the northwestern caused the PM 10 peaking at 826 µg m ) and OOA (6 µg m -3 ). The backward trajectory clustering analysis indicated the air mass from the southeast (at a frequency more than 30%) contained the higher NR-PM 1 concentration (more than 80 µg m -3 ) corresponding to the higher sulfate, nitrate and ammonium contributions.