The cobalt-ferrite nanoparticles (CoFe₂O₄ NPs) were prepared using the modified co-precipitation method and the CoFe₂O₄-SiO₂ magnetic composites were synthesized via st?ber step. The CoFe₂O₄-SiO₂ was also amino-functionalized to adsorb heavy metal ions. The crystalline phase, morphologies, particle size, chemical compositions and chemical structure of the absorbent have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The composites exhibited excellent magnetic properties with high saturated magnetization and can be separated by a magnet within 30 seconds, and the saturation magnetization (Ms) of CoFe₂O₄ NPs can be adjusted by sintering temperature,increased with increasing the temperature. The effect of pH and reaction time on the adsorption of CoFe₂O₄-SiO₂-NH₂ for Cu (II) was examined. And the amino-functionalized CoFe₂O₄-SiO₂ (CoFe₂O₄-SiO₂-NH₂) showed high adsorption capacity and the removal efficiency for Cu (II), Cd (II), Zn (II) and Mn (II), which makes great potential application on the heavy metal wastewater treatment.