Undoped hydrogenated silicon films have been prepared from a gas mixture of silane and hydrogen, at deposition temperature varying from 200—450℃ in an ultrahigh vacuum system using RFPECVD technique. Raman scattering, SEM and UV spectrophotometer are used to analyse the structure changes of microcrystalline silicon films throughout the deposition temperature range. Results show that at lower deposition temperature, the crystalline volume fraction of μc-Si:H films increased with the increasing of deposition temperature. Exceeding a certain temperature, the crystalline volume fraction decreased with further increasing of deposition temperature. This is attributed to a change in the dominant film growth process from surface-diffusion-limited at low deposition temperatures to flux-limited at higher deposition temperatures.