Two kinds of vertically aligned, well-ordered zinc oxide nanoneedle arrays were synthesized on silicon substrates without any catalyst by a simple thermal evaporation method. The nanoneedle arrays have uniform distribution and unique orientation and height. The field emission study shows that both of them have not only low turn-on field and threshold field, but also the ability of stable and long time emission. The low turn-on field and threshold field result from the high aspect ratio and thin apex of the nanoneedles. The stable and long time emission are due to the uniform distribution and good contact between the nanoneedles and the substrate. The results show that regular nanoneedle arrays are ideal candidates for flat panel field emission applications.