Abstract: From the view of healthy and environmental effects of particles, it is necessary to research the hygroscopicity of atmospheric particles, since it is an important factor to reflect their physical and chemical properties. The studies about the hygroscopicity in recent years were reviewed in this study. The typical equipment for hygroscopicity was hygroscopicity tandem differential mobility analyzer (H-TDMA) or improved H-TDMA. The G_f(observed growth factor) exhibited the single peak, two peaks or even multiple peaks. According to G_f, the particles could be divided into four types including pure insoluble, mixed insoluble, mixed soluble and pure soluble particles. The G_f showed higher values for particles in urban background sites than those for urban sites. The G_f for particles in urban area was higher in summer than that in winter and was higher during the daytime than that during the nighttime. The hygroscopicity of particles mainly depended on their chemical compositions and shapes. The G_f for pure soluble salt particles was usually higher. Fresh particles from diesel combustion showed less hygroscopic with low G_f, while their G_f could be enhanced with the particle aging and the fuel sulfur content increase. The G_f for particles from biomass burning was high and had obvious spatial variation. According to the domestic hygroscopic research status of atmospheric particulate matter, a key research direction was suggested for the future.