Light-emitting hydrogenated nano-crystalline silicon (nc-Si∶H) films have been fabricated using plasma-enhanced chemical-vapor deposition method.It was found that photoluminescence(PL) properties are directly related to grain size and surface strucuture.The quantum size effect and surface states model was proposed to explain PL.Meanwhile,temperature dependence of PL peak energy and integrated intensity are also studied.The former is mainly caused by band-gap shrinkage and the PL intensity decrease with increasing temperature can be interpreted using a temperature independent radiative term and a temperature-dependent thermally activated non-radiative one.