Abstract: A Fe₃O₄@ion imprinted poly(Styrene-3-(2-amino triethylenetetramine)-2-hydroxypropyl methacrylate-divinylbenzene) (Fe₃O₄@ⅡP(St-HPMA-DVB)) magnetic composite was synthesized via ultrasonic assisted suspension polymerization with perchlorate (ClO₄^-) as the ion imprinting template. The Fe₃O₄@ⅡP(St-HPMA-DVB) magnetic composite was characterized by TEM, vibrating sample magnetometer (VSM), TGA, XRD, elemental analysis (EA). The effect of the usage amount of crosslinking agent DVB while preparation on the structure and performance of Fe₃O₄@ⅡP(St-HPMA-DVB) magnetic composite was investigated. The results show that the Fe₃O₄@ⅡP(St-HPMA-DVB) magnetic composite has an average size of 500-2 000 nm, which increases with the increase of the amount of DVB. The saturation magnetization intensity is 9.77-12.78 emu/g, which decreases with the increase of the amount of DVB. The addition of DVB is beneficial to the formation and stability of the ion imprinted cavity of Fe₃O₄@ⅡP(St-HPMA-DVB) magnetic composite. The effects of solution pH value, initial concentration of ClO₄^-, and adsorption time on the adsorption properties of ClO₄^- in aqueous solutions were investigated. The results show that the adsorption capability is affected significantly by solution pH value and reaches the maximum at pH=3.0. The best adsorption capacity and selectivity of Fe₃O₄@ⅡP(St-HPMA-DVB) magnetic composite to ClO₄^- can be obtained when the usage amount of DVB is 0.5 g for synthesis. The adsorption mechanisms may be including both ion exchange and electrostatic interaction. The isothermal adsorption curves mainly obey the Langmuir mode with the maximum adsorption capacity (q_{m, c}=76.9-111.1 mg/g) much higher than that of none-ion imprinted polymer magnetic material Fe₃O₄@non-ion imprinted poly(NIP)(St-HPMA-DVB) magnetic composite (q_{m, c}=62.5 mg/g). The adsorption kinetic studies show that the adsorption processes reach the equilibrium within 10 min and the kinetic data are well fitted to the pseudo-second-order model. There is almost no interference by the coexisting components in water for the adsorption of ClO₄^-, with imprinting factor α at 1.8, and selectivity factor β lager than 5.8 for several kinds of common co-existing anions, respectively. The Fe₃O₄@ⅡP(St-HPMA-DVB) magnetic composite is an ideal candidate for adsorption and recycle ClO₄^- from aqueous solution.