The Gaoerqi deposit is a large silver-lead-zinc deposit newly discovered in Abaga Banner, Inner Mongolia, the western segment of Great Xing’an Range, indicating that the area has huge silver polymetallic prospecting potential. However, the genetic mechanism of the silver-lead-zinc deposit in the western section of the Great Xing’an Range is still unclear, and the difference in mineralization characteristics between it and the northern and southern sections is also unclear. This paper selects the Gaoerqi deposit to carry out research on the thermodynamics and isotope geochemistry of ore-forming fluids. The results show that the ore-forming fluids of the Gaoerqi deposit generally belong to the medium-high temperature (199~420℃), medium-low salinity (1.4%~17.9% NaCl.eqv) H2O-NaCl±CO2±CH4 system. The sulfides in-situ S (+6.78‰~+9.27‰) and in-situ Pb (208Pb/204Pb=38.301~38.338, 207Pb/204Pb=15.588~15.598 and 206Pb/204Pb=18.451~18.460) indicate that its ore-forming materials come from magma and surrounding rock strata. Fluid boiling accompanies the entire mineralization process, especially in the quartz-carbonate-coarse-grained arsenopyrite stage (S1); In the early stage of the quartz-polymetallic sulfide stage (S2), pulsed hot fluids are superimposed, and in the late stage, the system cools down and fluid mixing occurs, which leads to the gradual enrichment and precipitation of lead, zinc and silver in the main mineralization stage; The quartz-carbonate stage (S3) belongs to the late mineralization stage, and no sulfides appear. Comprehensive analysis shows that the mineralization characteristics and genetic mechanisms of the silver-lead-zinc deposits in the western section of the Great Xing’an Range, represented by the Gaoerqi deposit, are significantly different from those in other regions. It is proposed that the deposits are the product of magmatic activity under the background of oceanic subduction in the late Paleozoic, and a regional silver-lead-zinc mineralization model is constructed based on this.