From the electron paramagnetic resonance (EPR) experiments on ZnS:Mn 2+ nanoparticles and Pyrex glasses composites.we determined that there are three types of states of Mn 2+ in ZnS host lattice:substitution state (Mn 2+ ) sub ,interstitial state (Mn 2+ ) int and Mn clusters.We also observed that g factors increase with the decreasing of the radii of nanoparticles.The fitting of g values coincides well with the experiments.The g factor shift is due to the hybridization between sp 3 states of ZnS and 3 d 5 of Mn ions under carrier quantum confinement ( R