Nanocrystalline ZnO films is a promising material for short-wave laser and luminescence etc, due to its wide band gap (3.37 eV) and high exciton binding energy(60 meV)at room temperature.Nanocrystalline ZnO films is prepared by using sol-gel, grow on a quartz glass subtractes, Photoluminescence spectra and Absorption spectra of nanocrystalline ZnO films with excitation wavelength 365 nm are measured at room temperature.Two emission bands are observed, one being a narrow violet band its central wavelength is 395nm and the other being wide visible band its central wavelength is 524 nm, 450 nm.Crystal structure of samples are examined by X-ray diffraction (XRD) pattern, the mean grain size of nanocrystalline ZnO films are calculated by with Debye-Scherrer formula.The results indicate that nanocrystalline ZnO films has a hexagonal wurtzite structure and polycrystalline, and showed sharp diffraction peak for ZnO(002),which indicate that as-sputered film were highly c-axis oriented.In particular the mechanism behind......