We demonstrated that MnFe2O4 spheres could be successfully prepared in large-scale via a facile solvothermal process. The average size of final products over a wide range from 40 to 420 nm was remarkably influenced by the experimental parameters, such as reaction duration, surfactants, and initial concentration of reagents. The structure, size, morphology, and magnetic properties of final products were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, and vibrating sample magnetometer. The magnetic properties of final products varied with the change of experimental conditions. Preliminary results revealed that this approach could be successfully extended to the preparation of other ferrite compounds.