A Fe3O4 hybrid material (Fe3O4@SiO2-S2) modified by schiff base was prepared by grafting methyl acrylate (MA), ethylenediamine (EDA) and salicylaldehyde (SA) onto the prepared magnetic hybrid material Fe3O4@SiO2-NH2 successively, what's more, the structure was characterized by IR, XRD, SEM ,TEM and VSM. The results showed that the Fe3O4@SiO2-S2 has an abvious core-shell structure and a saturation magnetization of 45.9 emu/g. Study on the adsorption of aqueous heavy metal ions showed that Fe3O4@SiO2-S2 posed selective adsorption for Hg2+ with the saturated adsorption capacity of 362 mg/g(1.12 mmol/g), which was superior to Fe3O4@SiO2-NH2, Fe3O4@SiO2-HO-S and other adsorbents, at the condition of pH=6, 45 ℃, the adsorption capacity remained 89% after 5 cycles of adsorption-desorption, what's more, adsorption equilibrium was reached at about 300 min and the adsorption isotherm conformed to the Langmuir isotherm adsorption model.