Abstract: Nanometer ZnO films grown at low temperature were deposited on glass substrates by gas discharge reaction evaporation.By twice deposited the problem of film growing saturation could be solved, the film thickness effectively increased and film quality be improved. The grown mechanism of ZnO films was discussed. Their surface morphology and crystal structure was studied by atomic force microscopy (AFM) and X-ray diffraction (XRD). The results show that double layer nanometer ZnO films have better crystalline quality and stability. The films growth along the c-axis direction have little stress at grain boundary. The crystal grains size about 35 nm of the films is uniform and roughness of surface is lowered.