In order to develop low-cost well-aligned ZnO nanowire arrays with h igh quality,in this paper,ZnO nanowire arrays were fabricated on quartz glass substrates by chemical bath depo sition.The ZnO nanowire arrays were then annealed at 400℃,600℃ and 800℃ for 1h in Ar,respectively.Their m orphology,crystalline structure and optical properties were investigated using field emission scanning electron microscopy (FESEM),X-ray diffractometer (XRD),UV-Vis spectrophotometer and fluorescence spectrometer,r espectively.The results show that the average diameter of ZnO nanowires somewhat increases after annealing,a nd after being annealed at 800℃,the adjacent ZnO nanowires are bonded together.With the increase of annealing temp erature,the crystalline quality of ZnO nanowire arrays is gradually improved,and the crystalline quality is t he best when annealed at 600℃. Both the optical transmittance in the visible region and optical bandgap of ZnO nanowire arrays decrease as the annealing temperature increases.Only a weak near-band emission peak located at about 390nm can be observed for the unannealed and annealed samples at 400℃.When the annealing temperature is above 600℃,the near-band emission peak becomes strong sharply and a new weak green emission band can be f ound.