We report in this paper the observation of visible photoluminescence (PL) at room temperature from nano-crystallites of silicon films, which are prepared in a PE CVD system by using strong hydrogen diluted silane as the reactant gas source, without any post-processings. We attribute the PL to the photons above the band gap of bulk crystal silicon created by the carriers in the nano-crystallites under the function of quantm size effect. The effective deposition parameters are concerned.