The electron field emission from Si tips coated with nanocrystalline diamond films was investigated. The Si tips were formed by plasma etching, and nano-diamond films were deposited on the Si tips by hot filament chemical vapor deposition. The radius of curvature for the Si tips was averagely about 50 nm. The microstructure of the diamond films was examined by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ion-pumped vacuum chamber at a pressure of 106 Pa. The experimental results showed that the nanostructured films on Si tips exhibited a lower value of the turn-on electric field than those on flat Si substrates. It was found that the tip shape and non-diamond phase in the films had a significant effect on the field emission properties of the films. The electron field emission from Si tips coated with nanocrystalline diamond films was investigated. The Si tips were formed by plasma etching, and nano-diamond films were deposited on the Si tips. The radius of curvature for the Si tips The microstructure of the diamond films was examined by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ion-pumped vacuum chamber at a pressure of 106 Pa. The experimental results showed that the nanostructured films on Si tips exhibited a lower value of the turn-on electric field than those on flat Si substrates. It was found that the tip shape and non-diamond phase in the films had a significant effect on the field emission properties of the Films.