Abstract: In the present report ZnO nanocrystals were prepared by precipitation method from Zinc Chloride and Ammonia in aqueous solutions at a pH value 8.0 .ZnO nanocrystals were then synthesized by heating the precursor in a muffle furnace at temp 350°C for 3 hours and allowed to cool to room temperature. The obtained ZnO nanoparticles have been studied using characterization techniques like X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy dispersive analysis Of X-ray (EDAX). XRD results reveal that the sample is crystalline with a hexagonal wurtzite phase. X-ray peak broadening analysis was used to evaluate the crystallite sizes and lattice strain by the Williamson-Hall (W-H) analysis. Further appropriate physical parameters such as strain, stress, and energy density values were also calculated using W-H analysis with different models, viz, uniform deformation model, uniform deformation stress model and uniform deformation energy density model. SEM and EDAX study confirms the preparation of ZnO nanoparticles.