The Huayuan leadzinc deposit is expected to become the biggest PbZn deposit in China, and one of the worldclass superlarge ore deposits with more than ten million tons of lead and zinc resource reserves. In this paper, C, O, H, S, Pb and Sr isotope geochemistry were analyzed in this paper in order to understand comprehensively the source of the ore metals and ore fluids. The analysis results show that δ13CPDB values of calcite samples display a range of 2.71 ‰ to 1.21 ‰, the δ18.OSMOW values in a range of 16.09 ‰ to 22.48 ‰. In the Huayuan leadzinc deposit, the carbon in the oreforming fluid is mainly derived from marine carbonate dissolution. The δ13CPDBvalues of surrounding rock in Huayuan leadzinc deposit range of 0.29 ‰ to 1.05 ‰, the δ18OSMOWvalues range of 21.33‰ to23.89‰, the surrounding rock is sedimentary marine carbonate. The δ34SV-CDT values of sulfides are 24.93‰～34.66‰, and the 34S values of barite are 32.78‰～34.22‰, suggesting that the sulfur should be derived from the insitu thermochemical reduction of sulfates from the sedimentary strata. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values of the ores are in the range of 17.999～18.919, 15.554～15.798 and 38.088～38.576 respectively, and the normal Pb model ages are 437~534 Ma, so the ore metals were likely derived from the OrdovicianCambrian strata. The δDSMOWof fluid in calcite and sphalerite changes from 91.1‰ to 15‰, the δ18Ofluidrange of 4.1 ‰ to 8.75 ‰, The δDSMOWδ18Ofluiddiagram shown that, the main source of oreforming fluid is formation water and atmospheric precipitation. Waterrock reaction between oreforming fluid and wall rock is the main mechanism leading the precipitation and crystallization of calcite and sphalerite in Huayuan PbZn deposit, west Hunan. The initial 87Sr/86Sr values of the oreforming fluid are 0.70906~0.71022, higher than 87Sr/86Sr values (0.70886~0.70921) of the host rock Cambrian limestone, implying that the oreforming fluid probably migrated through the underlying formation of Qingxudong Group, and experienced waterrock reaction and isotope exchange between the ore fluid and the shale, clastic rocks and mudstones which had high 87Sr/86Sr values.