Fe3O4/ABc composite was prepared by using chemical precipitation, the physical and chemical properties of biochar were analyzed by XRD、SEM、FT-IR and VSM. Batch experiments were carried out to investigate the effects of solution pH , adsorbent dosage on sorption efficiency and the adsorption kinetics, isothems were investigated. The results showed that Fe3O4@ABc composite with paramagnetic property was prepared successfully by compositing Fe3O4 with sludge biochar(ABc), and it could be utilized easily under external magnetic field. The specific surface area and average pore size of Fe3O4@ABc is 622.88 m2?g-1 and 1.56 nm, and removal rate of methyl orange attained 96.14 %, when the concentration of methyl orange is 100mg ? L-1, the addition amount is 10 mg, the adsorption time is 240 min. The adsorption data fitted well with the pseudo-first order kinetic model and Freundlich isotherm model，which indicates that physical adsorption is the main adsorption mechanism and chemical adsorption is the auxiliary adsorption mechanism