The Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province, located in the western margin of the Yangtze Block, is one of the important bases for the production of base metals in China. The Maoping large-scale Pb-Zn deposit, occurred in the middle of this province, is the second largest Pb-Zn deposit. Its proven total Pb and Zn metal reserves exceed 3Mt, and the average grade of Pb + Zn is 12% similar to 30% , with a local reach of 45%. The ore bodies occur as a layered, lenticular or veined shape distributed in the NW inverted wing of the Maomaoshan anticline and its inclined end NE interlay fault zones. The Maoping deposit mainly consists of three ore bodies (groups), of which the No. I ore body ( group) is hosted in the Upper Devonian Zhaige Formation dolostone, the No. II ore body ( group) is hosted in the Lower Carboniferous Baizuo Formation dolostone, and the No. III ore body ( group) is hosted by dolostone of the Upper Carboniferous Weining Formation. The ores are mainly composed of ore minerals, such as sphalerite, galena and pyrite, and gangue minerals, for example, dolomite and calcite with a small amount of quartz and barite. Those hydrothermal minerals have massive, disseminated or veined structures, and have granular, metasomatic, co-edge, colloidal, aggregate or fragmentation textures. Hence, the epigenetic ore-forming characteristics of the Maoping deposit are obvious. The Nano-SIMS in-situ S isotopic compositions show that the fine-grained strawberry aggregate pyrite and colloidal sphalerite had a significant depletion of S-34, and their delta S-34 values range from -20.4 parts per thousand to -8. 7 parts per thousand. Such sulfur isotope signatures have typical biogenetic sulfur characteristics, suggesting that they had undergone marine sulfate bacterial reduction process ( BSR) On the other hand, the in-situ delta S-34 values of granular pyrite and sphalerite vary from 22. 1 parts per thousand to 25. 6 parts per thousand, obviously enriched in heavy sulfur isotopes, indicating that they had undergone a marine sulfate thermochemical reduction process ( TSR) . Since BSR and TSR are mainly temperature dependent, the formation of S2- in the Maoping deposit was local reduced and may first undergo a relatively low temperature BSR process, and then undergo a relatively high temperature TSR process. The fs LA-MC-ICPMS in-situ Pb isotopic ratios of galena show that Pb isotopic ratios of galena are relatively uniform, suggesting that the source of Pb is single or well-mixed. The comparison indicates that the ore-forming metals of the Maoping deposit were mainly derived from ore-bearing sedimentary rocks with a certain influence of underlying basement rocks. In addition, the in-situ Pb isotopic ratios of galena have a tendency to increase with the increase of the elevation, suggesting that the migration direction of the ore-forming fluid is most likely upward, and with the evolution of ore-forming fluids, the radiogenic Pb-rich sedimentary rocks contributed more ore-forming metals. Hence, this paper considers that the Maoping large-scale Pb-Zn deposit is the product of fluid mixing and its deep may have a good prospecting potential, as the metal-rich basements contribute more in deep.