Undoped ZnO nano particles and Ni doped ZnO nanoparticles prepared by chemical precipitation method and assessed for their structural, morphological and optical properties. The prepared undoped and Ni doped ZnO nanoparticles were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectral (FTIR), UV-Visible spectrophotometer, Scanning electron microscopy (SEM) and Energy Dispersive X-ray analysis (EDAX), Photoluminescence spectra (PL). XRD pattern shows the purity of prepared undoped and Ni doped ZnO nanoparticles size. Scanning electron microscopy (SEM) observations revealed remarkable change in morphology of the prepared samples. The presence of functional groups and chemical bonding was confirmed by FTIR and UV analysis. The defect states were revealed from the UV and visible emissions of the photoluminescence spectra.