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.