Abstract: Heavy metal contamination in soils, particularly Pb²⁺ pollution, presents significant environmental and geotechnical concerns. This study evaluates the effectiveness of microorganism-induced phosphate precipitation(MIPP)for stabilizing lead-contaminated soils and compares the performance of different cementing solutions in enhancing mechanical properties and immobilizing lead. Sodium glycerophosphate(SGP)was used as the phosphorus source, with MgCl₂(S-Mg group)and CaCl₂(S-Ca group)introduced as auxiliary cementing agents. A series of laboratory tests—including unconfined compressive strength(UCS), direct shear tests, and toxicity characteristic leaching procedure(TCLP)analyses—were conducted under varying curing times(3, 7, 14, and 28 days)and Pb²⁺ concentrations. The underlying mechanisms were further examined based on microbial activity, precipitation behavior, and mineral phase formation. The results indicate that MIPP treatment significantly improved the UCS and shear strength of Pb-contaminated soils, with the S-Ca group showing the most notable enhancement. After 14 days of curing, the peak UCS of the S-Ca group increased by up to 19.88% compared to other groups, while its peak shear strength rose by 36.36%. TCLP analyses confirmed that Pb²⁺ concentrations in leachates from S-Ca-treated soils remained below 0.1 mg ·L^-1, complying with regulatory standards. Mechanistic investigations revealed that Ca²⁺ addition alleviated the toxic effects of Pb²⁺ on bacterial activity and promoted the formation of stable phosphate minerals, such as Ca₂Pb₃(PO₄)₃Cl, thereby improving both soil structure and long-term stability. MIPP proves to be an effective and sustainable technique for stabilizing Pb-contaminated soils, enhancing mechanical strength while effectively controlling Pb²⁺ leaching. Among the tested cementing solutions, the CaCl₂-based system(S-Ca group)achieved an optimal balance between performance and cost-effectiveness, demonstrating strong potential for practical application in heavy metal-contaminated soil remediation.