The ZnO ultrathin films were fabricated from annealing the ZnS nanoparticulate films. By the layer by layer self-assembly technique, we constructed the ZnS nanoparticulate films from alternating layers of ZnS nanoparticles and polydiallyldimethylammonium chloride (PDDA). The result of the emission spectra indicated that PDDA played a role of passivator. Annealing the ZnS/PDDA films at different temperatures led to the changes in absorption. The SEM images showed that the preannealed film was composed of the uniformly distributing domains, while on the annealed film, there exist some holes formed by the burning of the organic components. The EDS confirmed that ZnS could be converted to ZnO at 500℃