ZnO crystals have attracted a great attention for next generation nanodevices because it has a superior crystalline quality, a better electrical/optical quality, a freedom to choose substrate and a large surface area to volume ratio. We have been succeeded in growing nano-structured ZnO crystals by nanoparticle-assisted pulsed-laser deposition without using any catalyst. Not only vertically aligned ZnO nanowires but also horizontally aligned ZnO nanowires have been successfully grown on the annealed c-plane and a-plane sapphire substrates, respectively. Besides, Depending on the PLD growth conditions and the composition of the target, ZnO nanowalls with thickness of tens of nanometers and dimension of several micrometers were synthesized. The room temperature photoluminescence spectrum of such a ZnO nanowall exhibited a strong intrinsic UV emission and a week defect-related visible emission. Synthesized ZnO nanowires were applied to a heterojunction light-emitting diode and an UV photo-sensor. In addition, it was found that the ZnO nanowalls showed stable field emission properties with low threshold field and a big field enhancement factor. Furthermore, layer-structured ZnO nanowires were fabricated by NAPLD using a multi-target changer system.