MNPs are widely used in biotechnology, magnetic resonance imaging, catalysis and other areas. In this paper, we propose a simple, quick, inexpensive and efficient way to prepare amino-MNPs with sonication-assisted process. The amino-MNPs prepared by hydrolyzing TEOS and APS were characterized by SEM, TEM and FTIR. Conjugation of SA and amino-MNPs was also studied. The biotin bound capacity of prepared SA coated amino-MNPs was 1.824 nmol/mg, which well meet the need of biological application.