The magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared by a simple and "green" method using functionalized SiO 2 spheres as templates. Magnetic particles (Fe 3 O 4 ) were deposited on the SiO 2 surface by varying the molar ratio of [Fe 2+ ]/ [Fe 3+ ] and the molar concentration of iron salts. The obtained magnetic hollow silica spheres exhibited a super-paramagnetic behavior at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder scattering (XRD) were applied to characterize the MHSS. Besides, their unit cell parameters are calculated according to results indexing to XRD, the MHSS sample prepared at 0.10 M iron salts and 2:1 molar ratio of [Fe 2+ ]/ [Fe 3+ ] has a largest cell angle (β) of unit cell. Due to large hollow cavity space and super-paramagnetic characteristics, the inner amino-functionalized MHSS could be labeled with radioisotope 99 Tc m to study the MHSS's magnetic targeting distribution in vivo. These results indicate that the MHSS has potential in the magnetic targeted drug delivery system which reduces the damage to normal cells and improves the therapeutic effect of cancer.