Abstract: The addition of phosphate (P) and calcium (Ca) in the mineralization process of lead (Pb) by microorganisms can promote the formation of stable mineralization product of Pb, and therefore effectively reduce Pb pollution in the environment. In this study, a Pb-tolerant strain, Bacillus C075, was selected from the soil contaminated by heavy metals around a mining area. P and Ca were added to the Pb-microbial-mineralization process in order to understand the effects of P and Ca on Pb mineralization. The results showed that phosphate had no obvious effect on the growth of the strain. When the Ca²⁺ concentration was 10 mmol/L, the strain could get optimum growth condition and the tolerance of the strain to Pb was enhanced. The addition of P and Ca could increase the Pb mineralization rate by 23.6% and 56.9%, respectively. During the mineralization process, the K_m (Michaelis constant) measured by the kinetic curve was 271.53 μmol/L, and the V_max (maximum enzymatic reaction rate) was 109.53 mg/(h·g), indicating that the strain had good phosphatase activity, which was beneficial to the mineralization process. The FT-IR and XRD patterns showed that the mineralization products with or without P addition were Pb₅(PO₄)₃OH, but the addition of P increased the adsorption area and adsorption sites on the surface of the strain, and improved the mineralization rate. After adding P and Ca at the same time, a more stable mineralization product Ca₂Pb₈(PO₄)₆(OH)₂ appeared. The addition of P and Ca could make the resulting mineralization products more stable and compact, therefore improving the strain's tolerance to Pb and the mineralization efficiency. This study shows that the addition of P and Ca can increase the mineralization rate of Pb by the strain and generate a stable mineral, which provides a reference for improving microbial mineralization and remediation of Pb.