Atmospheric particles play important roles in the cloud formation and global radiation balance and thus the climate. The aerosol particles over South China Sea (SCS) are influenced by complex surrounding environments and a variety of natural and anthropogenic sources. In this study, elemental composition and mixing state of atmospheric particles collected over the SCS during summertime 2021 were investigated based on the single particle analysis by computer-controlled scanning electron microscopy and energy dispersive X-ray spectrometer. Particles influenced by air masses from west Pacific had more fresh sea salt and the highest mixing state index, indicating clean remote marine source with internally mixing particles. Particles influenced by biomass burning in South East Asia had higher number fraction of potassium-containing particles with lower mixing state indices, indicating more externally mixing particles. Particles influenced by air masses from Philippines and the SCS mainly consist of sulfate and organic/sulfate, with the lowest mixing state indices. We showed different types of particles with various mixing state with the impacts from different sources.