Abstract: Polycrystalline diamond films were produced at different concentration of CH₄ through bell-jar type microwave plasma chemical vapor deposition apparatus at low power,using H₂-CH₄ as source gas. The renucleation of diamond films was examined and analyzed by using scanning electron microscopy,X-ray diffraction and Raman spectroscopy. The results show that the methane concentration has a significant effect on the renucleation of diamond films. With the increase of the concentration ratio of methane(1.0%~2.5%),the renucleation ratio was increased,the grain sizes were decreased as well as the diamond phase. While the diamond film gradually tend from (111) to (220) and (311) faces growth.