Nano-crystalline silicon films were prepared from SiH4 diluted with hydrogen by plasma enhanced chemical vapor deposition at a pressure of 230 Pa. The effect of hydrogen dilution on their growth rate and crystalline properties were investigated. The experimental results indicate that the crystalline fraction and grain size increase with increasing hydrogen dilution ratio, and when the hydrogen dilution ratio increases to 99%, the crystalline fraction reaches 70%. The deposition rate decreases with increasing hydrogen dilution ratio, when the hydrogen dilution ratio decreases from 99% to 95%, the deposition rate of thin film increases from 0.3nm/s to 0.8nm/s.