///The Ni-Mo polymetallic deposits hosted in Early Cambrian black rock series in the Zhangjiajie Sancha of Hunan Province and Zunyi Huangjiawan of Guizhou Province, China are the two representative cases of such deposits in southern China and even worldwide. Mineralogical features of the two deposits were revealed by relatively comprehensive analyses in this paper. The results show that pyrite is the primary mineral phase in the non-mineralized black shales. In contrast, a variety of minerals present in ore beds, including C-Mo-S mixed-layer phase (MoSC), millerite, pyrite and cellophane. Mineral elements Mo and Ni primarily presented in C-Mo-S and millerite and sourced from sea water and hydrothermal fluid, respectively. The origin of the deposits is influenced by mixing effects of seawater, hydrothermal fluid and bio-organic matter.