Magnetic biochar ( MB) spheres were prepared using the pine sawdust and sodium alginate as carbon sources, FeCl3 as the cross-linking agent and magnetization agent. Synchronous molding and magnetization were realized by the cross-linking reaction between sodium alginate and FeCl3. The MB was characterized by analysis methods such as BET, SEM, XRD, FT-IR and VSM. The results proved that MB had large specific surface area and good pore structure. MB showed good magnetism because its surface was successfully loaded with Fe3O4. The surface of MB prepared by low-temperature pyrolysis was rich in oxygen functional groups, so it was easy to complex with Pb (Ⅱ). When initial pH=6, MB addition=10% and adsorption time = 24 h, the optimal removal rate and adsorption capacity of MB prepared by 300 ℃ pyrolysis were 67.53% and 3.11 mg/g, respectively. The adsorption process fitted the quasi second order kinetics equation, and was mainly chemical adsorption. After adsorbing Pb (Ⅱ) in soil, MB could be separated and recovered by external magnetic field, and the recovery rate was more than 95%. After 5 times of regeneration, MB could still maintain 71% of the initial adsorption of Pb (Ⅱ).