Two (111) mirror Si substrates have been scraped with diamond powder and different time length.Both are still mirror polishing after scraping.The the diamond film with 5 cm diameter is prepared by microwave plasma chemical deposition system with same growth parameters and same mixture gases of H2,CH4,and O2.Diamond films morphology is analyzed by SEM and XRD spectra.Both show the similar crystal structure with the main diffusion peak(111),and XRD shows that the film grown at long time scraping substrate has amount of amorphous material.The thermal conductivity of the two diamond film and Si substrate are 241.7 W/mK,192.9 W/mK and 169.3 W/mK,respectively.The effects of substrates scraped on thermal conductivities are discussed in detail.