In this study, zinc oxide (ZnO) nanoparticles were synthesized by spray pyrolysis method. The properties of ZnO nanoparticles are determined by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-vis spectroscopy. Nematic liquid crystal mixture E7 was doped with 1, 2, and 4% ZnO. We investigate electrical and optical parameters of pure and doped nematic liquid crystal mixture E7. The experiments related to voltage dependence and light transmittance of the pure and doped E7 were carried out. The values of threshold voltage, total phase retardation and birefringence are examined. The results show that doping zinc oxide nanoparticles into liquid crystal mixture E7 decreases threshold voltage significantly.