Air pollution is an important threat to human health. Atmospheric particulate matters (PM), as one of the major air pollutants, have received increasing attentions in previous studies. Longtime exposure to PM especially the ultrafine particulate matters (UPM) smaller than 0.1 micrometers which can go directly to the alveoli of the lungs, has become a major health hazard. In this study, we investigated UPM pollution to analyze its source, composition and distribution characteristics of UPM in ambient air. We also summarized the existing detection technologies for UPM and analyzed their advantages and disadvantages. This study will provide a theoretical reference for environmental air protection and pollution control in China.