To characterize the hydrothermal sedimentary lithofacies of the Leji large- scale barite deposit and analyze the tectonic—lithofacies—paleogeographic units of its hydrothermal sedimentary basin.Methods:Field measurement of tectono—lithofacies sections and compilation of tectono—lithofacies logs from borehole cores.Results: The hydrothermal sedimentary system of the Leji barite deposit comprises distinct lithofacies assemblages. The barite- dominated system includes nine hydrothermal sedimentary lithofacies (e.g., barite hydrothermal synsedimentary lithofacies, siliceous—barite hydrothermal mixed sedimentary lithofacies). The siliceous hydrothermal sedimentary system comprises six distinct lithofacies (e.g., siliceous rock facies with allochthonous breccia, slump siliceous breccia facies). These assemblages formed within the Zhenning—Ziyun secondary pull—apart basin, situated between the northern margin of the eastern Tethys restricted ocean basin and the Yangtze paleo- continental margin.Conclusions: The Leji barite deposit is hosted within a third- order hydrothermal sedimentary basin, controlled by synsedimentary fault zones. The basin architecture can be reconstructed into five intra- basin tectonic—lithofacies—paleogeographic units: basin margin facies, hydrothermal vent conduit facies, basin plain facies, basin center facies, and third- order basin- bounding tectono—lithofacies. The basin center and hydrothermal vent conduit facies constitute the primary ore- hosting tectonic—lithofacies units.