Mn 1− x Zn x Fe 2 O 4 nanoparticles were prepared by hydrothermal synthesis at 200°C for 12h and characterized by X-ray powder diffraction (XRD), FESEM and vibrating sample magnetometer (VSM) techniques. The additions of Zn 2+ ions content reduced the nanoparticles size. With the increase of Zn 2+ ions content, the Curie temperature (T c ) increased firstly and then decreased; when x=0.3 the T c reaches the maximum value (430K). The results could be explained that the Zn 2+ ions changed spin ordering to increase the T c in the range of x⩽0.3, and magnetic properties were decreased because of increase of nonmagnetic Zn 2+ ions in the range of x>0.3.