The structural and optical properties of ZnS nanoparticles embedded in PVA films by an ion complexation method are reported. The results of TEM exhibit that the ZnS nanoparticles are well distributed in PVA films and their size can be controlled in the range of 2 nm～7 nm. ED analysis show that the ZnS nanoparticles have the similar structure of β-ZnS bulk material. Emission peaks of the nanoparticles vary in the range of 414 nm～440 nm at room temperature, depending on the experimental conditions. The relationships between ZnS nanoparticle morphologies and the PL emission peaks, intensity are emphatically discussed and their different mechanisms of luminescence are explored.