i>Qinggaoni is a common material in archaeological explorations. The practice of placing Qinggaoni in burial pits for sealing purposes originated in the Neolithic Age, gained popularity in the Shang Dynasty, prevailed from the Zhou to Han Dynasties, and reached its peak in the Qin and Han Dynasties. However, relatively few studies have focused on Qinggaoni, especially on humus, which affects the structural properties of Qinggaoni. In this study, a synchronous laser diffraction and dynamic image particle analyzer (LDPA), a scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS) and a Fourier transform infrared spectrometer (FTIR) were used to analyze the particle size, micromorphology, composition and humus properties of the Qinggaoni samples excavated from different sites in the Lanling Tashan tombs, Shandong Province. The results show that the inorganic minerals present in the Qinggaoni mainly include quartz, albite, muscovite, hydroxy-iron oxide, ferrihydrite and biotite. These minerals have a large specific surface area and surface charge, and they were combined with humin (which has a high content in organic humus and is closely bound to minerals) and humic acid (which has colloidal properties) to form a stable inorganic-organic complex. Among the samples, those from Tomb M166 show a large specific surface area and broader particle size distribution. Microorganisms such as Bacillus cereus are also enriched on the surface, providing favorable conditions for the formation of humus in the paste.