Abstract: Lead-zinc smelting activities have generated large amounts of slags, wastewater, and historically contaminated sites, resulting in persistent accumulation of Pb, Cd, Zn, and other heavy metals in soils and subsurface environments. These sites generally exhibit complex multi-metal contamination and long-term ecological risks. Conventional physicochemical remediation methods can rapidly reduce pollutant levels, but they often cause strong disturbance, require high costs, and show limitations in ecological restoration. In-situ microbial remediation provides a sustainable strategy by regulating microbial metabolism and interactions among microorganisms, minerals, plants, and soil environments. Through adsorption, complexation, redox transformation, mineral precipitation, and speciation regulation, microbial processes can reduce heavy metal mobility and bioavailability.This review summarizes the mechanisms, technical pathways, and engineering applications of in-situ microbial remediation for heavy metal contaminated lead-zinc smelting sites. Six major approaches are discussed, including biostimulation, bioaugmentation, microbially induced mineralization, microbial-mineral synergistic immobilization, plant-microbe combined remediation, and microbial electrochemical technologies. The applicability of these technologies in contaminated soils, smelting residues, and ecological restoration areas is analyzed. Typical applications, including sulfate-reducing bacteria induced sulfide precipitation, microbial-mineral synergistic stabilization, and microbially induced mineralization, are further discussed for controlling Pb, Cd, and Zn contamination risks.Although considerable progress has been achieved, practical applications of in-situ microbial remediation at lead-zinc smelting sites are still limited by insufficient microbial colonization stability, weak adaptability under complex contamination conditions, and incomplete evaluation of long-term remediation performance. Future studies should focus on targeted enrichment of indigenous functional microorganisms, optimization of multi-process coupling strategies, intelligent regulation of remediation processes, and site-specific remediation frameworks. These efforts will facilitate the transition of microbial remediation technologies from laboratory research to engineering applications and provide scientific support for green mine development and ecological restoration of mining and metallurgical legacy sites.