This paper is focusing on the synthesis of Zn1-xFexS nano-particles with x = 0, 0.1 and 0.2 by chemical co-precipitation method, the prepared of which are characterized by XRD, EDS, TEM, PL, magnetization versus field behavior and M-T curve. In the XRD patterns, Zn1-xFexS nano-particles are shown of cubic zinc blende structure, and the broadening diffraction peaks consistent with the small-size characteristic of nano-materials. The diameter of nano-particles is between 3.3 and 5.5 nm according to the HR-TEM images. The EDS data confirm the existence of Fe ions in Fe-doped ZnS nanoparticles. There we found that Fe-doping did not import new energy bands or defect states, but reduced the intensity of PL peaks. The magnetization versus field behaviors were illustrated by the M-H curves at both 5 K and 300 K, respectively, where no remanence or coercive force was observed. This phenomenon indicates that the Zn1-xFexS (x = 0.1) nano-particles are superparamagnetic. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves further reveal that the blocking temperature (T-B) of the superparamagnetic behavior might be below 5 K. (C) 2011 Elsevier B. V. All rights reserved.