Nanocrystalline silicon films were prepared by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique with SiH4 and H2 precursors. The micro-structure and the bonding characteristics of deposited films with different hydrogen dilution ratios were studied by Raman scattering spectroscopy and Fourier transform infrared absorption (FTIR) spectroscopy. The results show that with the increase of hydrogen dilution ratios, the thin film crystallization rate obviously improves to a certain extent, however, with the further increase, the film crystallization rate shows a downward trend. The analysis of infrared absorption spectra shows there is a close relationship between the silicon-hydrogen bonding model and the crystallization characteristics. With the continuous improvement of the hydrogen dilution ratios, the SiH2 bond density and the total hydrogen content in the film reduce significantly. In conditions of high hydrogen dilution ratios, the intensification of dehydrogenation reaction lead to the SiH2 bond density and the total hydrogen of film increases, and lead to a decline in the rate of film crystallization.