Atmospheric aerosol particles play a crucial role in weather and climate change, air quality, as well as human health. There is a huge diversity of particle types and complex internal mixing for the individual particles. The combination of the complementary aerosol mass spectrometry, i.e., single particle measurements with single particle mass spectrometer and bulk measurements with aerosol mass spectrometer, can help us to better investigate the external and internal mixing state of the aerosol particles, and further understand their evolution in the atmosphere.