Abstract: The Shuiyindong superlarge gold deposit, located in southwestern Guizhou Provence, has a high-grade layered orebody in the Upper Permian Longtan Formation(P₃l).It is controlled by specific impure carbonate rocks and favorable lithology.In this paper, the authors summarized constraints on the sedimentary facies and rock characteristics of the Longtan Formation.Based on a detailed and systematic petrographic comparative analysis of the host rocks and wall rock, the authors hold that the Longtan Formation consists of a set of shallow-water delta peat bogs and coastal tidal flat lagoon sediments characterized by rich organic matter.Limestone interlayers in Longtan Formation may represent transgressive events of different periods.The Emeishan basalt magma eruption changed Wujiapingian epoch sedimentary paleogeographic pattern and composition of terrigenous clastic rocks in the formation of the Longtan Formation and developed sediments related to volcanic activity; iron dolomite in the ore might have been a thermal alteration product of volcanic clastic material; organic matter and basaltic volcanic fragments in impure bioclastic limestone was an important controlling factor for the abnormal enrichment of gold to form high-grade orebodies.When looking for this type of gold deposits in southwestern Guizhou Provence, researchers should focus on the evaluation of the favorable lithological unit.