ZnO nanostructures with different morphologies of nanorods, nanoneedles, nanowires, and nanobelts have been synthesized by thermal evaporation of pure ZnO micropowder. Based on the appearance of the as-synthesized products observed by field emission scanning electron microscope (FE-SEM), we show that substrate temperature and catalyst are the critical factors for the formation of different morphologies of ZnO nanostructures. The photoluminescence (PL) properties of the ZnO nanostructures were investigated. The difference in PL spectra both in intensity and structure for the different ZnO nanostructures are presented. We demonstrate that under appropriate synthesis conditions, highly crystallized and defect-free ZnO nano-structures can be obtained.