The (Pb-Zn)-Ag-Ge deposits of the Qilinchang deposit (Western Yangtze Platform, southwest China) are hosted by a 20 m thick sequence of Early Carboniferous carbonate rocks of the Baizuo Formation. Sulfide mineralization consists mainly of pyrite sphalerite, galena, chalcopyrite, and marmatite, while gangue minerals are dolomite, calcite, and quartz. Bulk carbon and oxygen isotope analysis were determined on syngenetic calcite associated with mineralization. The delta C-13(PDB) and delta O-18(SMOW) values range from -2.35 to -0.37 parts per thousand and +19.24 to +26.83 parts per thousand, respectively. These values reveal that the ore-forming fluids were predominantly derived from water/rock interaction between the mantle/metamorphic fluids and carbonates. Sulfur isotope compositions range from +12.33 to +17.01 parts per thousand are consistent with thermochemical reduction (TSR) of Carboniferous seawater sulfate. Sulfur is mainly derived from evaporite rocks hosted in the strata, relatively producing H2S-rich fluids evaporated by TSR. The homogenous lead isotope ratios for galena and sphalerite suggest that Pb was sourced from the basement rocks of Kunyang Group and Cambrian to Permian strata. The total REE (SREE) compositions for calcite, pyrite, galena, and sphalerite indicate that the input of REE in the fluids was probably obtained from carbonate host rocks. All combined data propose multiple or mixed sources.