The Zhen’an-Xunyang is a Late Paleozoic fault-depressed basin in the southern Qinling region. A large number of lead-zinc deposits are distributed along the arcuate fault zone at the southern margin of the Xunyang Basin, with existing reserves exceeding 200 Mt. These deposits are mainly hosted in the silty phyllite of the Meiziya Formation and Shuanghezhen Formation of the Silurian, and the ore bodies are predominantly stratified or banded, having undergone synsedimentary deposition and tectonic modification. In this study, the Gangou lead-zinc deposit located in the central part of the metallogenic belt was selected as the research object. Based on detailed field investigations, mineral fabric and geochemical analyses were conducted on the Gangou lead-zinc deposit. The main minerals in the Gangou lead-zinc deposit are predominantly sphalerite, with secondary minerals including galena, pyrite, and chalcopyrite, while the gangue minerals are mainly quartz and sericite. On this basis, fluid inclusion H-O and in-situ S-Pb isotope tests were carried out on quartz and metal sulfides from the main mineralization stages. Hydrogen and oxygen isotopes indicate that the ore-forming fluids are characterized by a mixture of magmatic fluids and organic waters, with the addition of meteoric water. The δ34S values of metal sulfides such as sphalerite and pyrite in the ore range from 3.43‰ to 6.46‰, suggesting that sulfur is primarily derived from depth and has mixed with sulfur in the strata. Lead isotopes indicate that the lead has a crust-mantle mixing characteristic, and the lead-zinc deposits in the area share similar geological and geochemical features. It is preliminarily concluded that the lead-zinc deposits within the Zhenxun Basin exhibit typical characteristics of sedimentary exhalative (SEDEX) lead-zinc deposits. Although later tectonic activities have modified the strata and deposits, their sedimentary features have been largely preserved, and the original host horizons and characteristics of the deposits remain consistent with their primary features.