The (100)-orientated diamond film was deposited by hot-filament chemical vapor deposition (HFCVD) technology with a positive DC bias voltage. The morphology,X-ray diffraction (XRD),RAMAN spectrum and dark current versus applied voltage characteristics analysis show that the positive dc bias can increase the nucleation density and (100)-orientated growth,making the growth of the high quality diamond film easier and cheaper than using other methods.