Large-area and uniform ZnO nanowires have been produced directly on a conducting brass substrate by annealing a Cu0.66Zn0.34 foil under a mixture of argon and oxygen. The morphology, structure, and composition of the ZnO nanowires are characterized by X-ray diffraction, electron microscopy, energy-dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy. The ZnO nanowires with diameters of about 40-70 nm and lengths up to micrometers grow preferentially along the [001] direction. Since the Cu0.66Zn0.34 foil serves as both the Zn source and substrate, the synthesis and assembly of the ZnO nanowires on a conducting substrate is accomplished in one step, and good intrinsic adhesion and robust electrical contact between the ZnO nanowires and conducting substrate are realized. This ZnO configuration forms an ideal field emitter and good field emission properties are corroborated in this study. Photoluminescence studies indicate that these ZnO nanowires have good optical quality exhibiting strong ultraviolet (UV) emission at 383 nm and a weak visible emission band centered around 485 nm at room temperature. The good field emission and optical properties suggest that ZnO nanowires fabricated by this method have promising applications in nano-optoelectronic and field emission devices.