SMn x Zn 1-x Fe 2 O 4 (x=1,0.9,0.8,0.7,0.6,0.5,0.25,0) nanoparticles were prepared by ball-milling hydrothermal and investigated by X-ray diffraction, DTG and TEM. Nanocrystallite grain size was determined by X-ray linewidth to be from 63 Å to 274 Å. The thermal properties indicate absorbed water still remain at low temperature, crystalline wate will be decomposed from 230 to 260 , partial Mn 2+ will be oxidized near 730 . TEM shows the ferrite particles pocess a spherical morphology and uniform nanosize.