Abstract: The Shuiquangou copper-polymetallic deposit is located in the middle-southern section of the Daxing'anling Mountains metallogenic belt. It is a strata- and structure-controlled deposit, and exhibits laminated and brecciated mineralization. Previous work on this deposit has primarily focused on ore prospecting, and genetic studies remain relatively insufficient, which has constrained the planning of subsequent exploration efforts. To further elucidate the genesis of the deposit, this study conducted systematic mineralogical observations, fluid inclusion analysis, and S-Pb isotopic testing. The results indicate that the mineralization process of the Shuiquangou deposit can be divided into three stages: Quartz-pyrite stage (early stage), quartz-chalcopyrite-galena-sphalerite stage (main mineralization stage, representing the primary enrichment phase for Cu, Pb, Zn, and Ag), and calcite-quartz-pyrite stage (late stage). Fluid inclusion studies reveal that the quartz-hosted inclusions are predominantly liquid-rich two-phase inclusions (with vapor-liquid ratios of 10%~30%). The homogenization temperatures of inclusions from the early stage range from 320°C to 350°C, with salinities of (13~15) wt%NaCleqv. For the main mineralization stage, homogenization temperatures range from 260°C to 290°C, with salinities of (9~11) wt%NaCleqv. In the late stage, homogenization temperatures range from 140°C to 220°C, with salinities of (6~9) wt%NaCleqv. These data reflect that the ore-forming fluid belongs to a moderate-temperature, moderate-salinity NaCl-H2O±CO2 system, and exhibits a gradual decrease in both temperature and salinity from early to late stages. Sulfur isotope analysis shows that δ34S values of sulfides range from -2.1‰ to 18.2‰, similar to seawater sulfur signatures. Combined with the Permian marine sedimentary setting of the mining area, it is inferred that sulfur was primarily derived from seawater. Lead isotope compositions range as follows: 206Pb/204Pb=17.501~20.42, 207Pb/204Pb=15.347~15.608, 208Pb/204Pb=37.799~38.531. Plots of lead isotope compositions on tectonic discrimination diagrams indicate that lead was mainly sourced from an orogenic belt. Based on the above comprehensive evidence, the formation of the Shuiquangou copper-polymetallic deposit involved two key processes: early-stage exhalative-sedimentary pre-enrichment and late-stage magmatic-hydrothermal superimposition and enrichment.