In current work the pure ZrO2 nanoparticles and with Ag impurity were synthesized by using sol-gel method. The absorption spectra and optical energy gap of these nanoparticles were investigated. The monoclinic and tetragonal phases of these nanoparticles were confirmed by X-ray diffraction (XRD).It was found that by doping of Ag to the ZrO2 structure, the particle size was increased. The field emission scanning electron microscopy analysis (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) demonstrated the morphology and formation of nanoparticles as well as the presence of Ag.The optical energy gap of Ag-doped ZrO2 decreased with respect to that of pure ZrO2.