The field:emission characteristics of diamond films with different surface morphologies were studied. The diamond films were grown on silicon substrates by chemical vapor deposition technique under different deposition conditions. The nucleation density and surface morphological properties were analyzed by means of scanning electron microscopy and atomic force microscopy. Results from these studies showed that the diamond film with small crystal size and high nucleation densities had better field emission characteristics,, In addition, (110) and (111) oriented films exhibited better field emission properties than (100) oriented films;