Fabrication and field emission properties of a ZnO nanowire (NW) triode were investigated in this study. The ZnO NWs have a single-crystalline wurtzite structure, ∼50 nm diameter and 3.4 × 1010 cm-2 number density. The ZnO NW triode shows good and controllable emission properties with the turn-on anode electric field (at a current density of 1 νA cm-2), threshold anode electric field (at a current density of 1 mA cm-2) and field enhancement factor of 1.6, 2.1 V νm -1 and 3340, respectively. The ZnO NW triode exhibits transistor characteristics with a gate leakage region, linear region and saturation region. Furthermore, the controllable field emission performance of the ZnO NW triode can be enhanced by illumination and argon ion bombardment. A low temperature Si-based microelectronic compatible fabrication process was provided for successfully making ZnO NW based triodes with good field emission properties.