<p>In this study, biochar (BC) was prepared by pyrolysis using sesame straw as the precursor, and modified with hydroxyapatite and chloroapatite to prepare hydroxyapatite-modified biochar (HBC) and chloroapatite-modified biochar (BC-Cl), respectively. The changes in functional groups before and after biochar modification were investigated using various characterization methods, and the passivation effects of BC, HBC, and BC-Cl on lead (Pb) in soil were studied. The three types of biochar were introduced into the contaminated soil at ratios of 3% and 5% to passivate the soil. Compared with CK, the TCLP extraction content of Pb in the 3% BC and 5% BC groups decreased by 45.45% and 68.18%, respectively. Compared with CK, the TCLP extraction content of Pb in the 3% HBC and 5% HBC groups decreased by 76.70% and 86.64%, respectively. Compared with CK, the TCLP extraction content of Pb in the 3% BC-Cl and 5% BC-Cl groups decreased by 82.38% and 93.75%, respectively. Moreover, the effective Pb content decreased with increased of biochar dosage. When the soil was cultured for 90&#xa0;days, the reducible Pb content of BC, HBC, and BC-Cl decreased by 22.03%, 22.97%, and 26.36%, respectively, compared with CK. BC, HBC, and BC-Cl effectively passivated Pb in soil, with the 5%BC-Cl soil sample exhibiting the most pronounced passivation effect. This study’s findings offer a new method for efficient utilization of sesame straw and provide a reference for developing apatite-based soil remediation materials.</p>