The hemicellulose-based magnetic hydrogel was prepared by free radical polymerization and in situ co-precipitation from corn cob. The properties of the magnetic hydrogel were characterized by means of ICS, scanning electron microscopy(SEM) and universal tensile testing machine. Moreover the adsorption properties on methylene blue were studied. The results show that the hemicellulose-based magnetic hydrogel has super-paramagnetism, with a maximum saturation magnetization intensity of 21.83 A·m2/kg and a maximum compression strength of 0.119 MPa. The adsorption properties on methylene blue are good as well and the removal rate reaches 97%. The prepared hemicellulose-based magnetic hydrogel has good swelling properties, super-paramagnetism and removal efficiency of methylene blue. Furthermore it has better application prospects.