Abstract: Activated carbon/iron oxide composite has been widely studied in the compound material field. As its unique microporous structure and specific surface area, activated carbon provides active sites for the precipitation of magnetic particles. Magnetic activated carbon was prepared by chemical precipitation and ultrasonic technique after persulfate oxidation pretreatment. It contains higher specific surface area, abundant functional groups and good magnetic response, with a relatively high surface area of 770 m2/g, large pore diameter of 2.11 nm, pore volume of 0.327 m2/g. Saturation magnetization (Ms) of 10.07 emu/g and high-Coerciv is helpful to the separation and anti-demagnetization ability of the magnetic activated carbon. Through static absorption experiment to test the adsorption capacity of activated carbon and magnetic activated carbon, the result show that magnetic activated carbon has a high adsorption capacity of 68.925 mg/L Pb(Ⅱ) and is far beyond that of activated carbon which capacity is 30.125 mg/L.