///In order to discuss the genesis and sources of the ore-forming materials of polymetallic layer of black rock series in oft-com:office:smarttags" />Guizhou Province, this paper analyzed the isotopic compositions of polymetallic layer of black rock series exposed in Jiangsuo, Zhenyuan County. The results have shown that lead mixture of crust is the source of polymetallic ore lead of black rock series, there is the character of rich uranium lead and lean thorium lead, more metallogenetic materials might have been provided by chemical sedimentations of rich uranium lead and lean thorium lead of underlying Dengying Formation of the Lower Cambrian Niutitang Formation. The lead source of ore-forming materials are mixture of mantle and crust being the main source, being combined results of magmatism, chemical sedimentation and ocean hydrothermal sedimentation participated in. The formation of polymetallic layer of black rock series is the result of superimposition of multiple mineralization, been characterized by the multiple source and polyphase episode.oft-com:office:office" />