The lasing characteristics and the alignment methods of ZnO nanocrystals were investigated for an application to ultraviolet (UV) laser diode (LD). ZnO nanowires and nanosheets were synthesized on a silicon substrate by a CVD method or nanoparticle assisted pulsed-laser deposition (NAPLD), and then those ZnO nanocrystals were examined by a photoluminescence (PL) method with a third-harmonic Nd:YAG laser (355 nm, 5 ns). The observed emission spectra showed the obvious lasing characteristics having mode structure and a threshold for lasing. The threshold power density of a ZnO nanowire and a nanosheet were measured to be 100 kW/cm2 and 5 kW/cm2, respectively. Furthermore, the threshold power was calculated to be 8.4 mW for a ZnO nanowire and 2.5 mW for a ZnO nanosheet. Then the oscillation mechanisms were discussed on those ZnO nanocrystals. We also observed the laser-induced motion (LIM) of ZnO nanocrystals when they were excited by ultraviolet laser beam.