Monodisperse ferrite spheres with tunable diameters ranging from 50 to 400 nm were successfully fabricated by introducing various structure-directing salts,using a simple solve-thermal synthesis in ethylene glycol (EG).The electron microscopy imagines showed that the obtained magnetite spheres are composed of smaller hollow particles.It was found that the experimental temperature,reaction time,as well as the salt species and content could significantly affect the diameter of Fe3O4 spheres.