Abstract: In this study, peanut shell was used as raw material to produce biochar by pyrolysis, and the product of biochar was modified by NaOH and KMnO₄, respectively. Characterization results showed that the microstructure of the modified biochar was relatively dispersed, the pore size was decreased, and the stability was enhanced. The specific surface area of NaOH modified peanut shell biochar(AB) and KMnO₄ modified peanut shell biochar(MnB) increased up to 3.178 times and 5.065 times than that of peanut shell biochar(B), respectively. When KMnO₄ was used as modifying agent, manganese oxide was successfully fixed on the biochar. The zero point charge (pH_PZC) of B, AB, and MnB were 2.193, 2.888, and 2.466, respectively. The adsorption performance of Pb²⁺ using biochar before and after modification was investigated. It was found that the optimum pH values for the adsorption of Pb²⁺ using B, AB, and MnB were 4.5-6.5, 5.5-6.5 and 5.0-6.5, respectively. When the removal rate of Pb²⁺ was the same, the biochar dosage was MnB < AB < B, and the equilibrium adsorption time of Pb²⁺ using AB and MnB was shortened by 180 and 480 min, respectively. The adsorption kinetics model and isotherm model showed that the Pb²⁺ adsorption process was controlled by chemisorption in three biochars, and the order of adsorption rates was MnB>AB>B. The maximum theoretical adsorption amounts of AB and MnB were 53.19 and 80.65 mg/g, which were 1.38 and 2.10 times than that of B, respectively.