We have studied the effects of the laser fluence on the characteristics of ZnO nanoparticles produced by pulsed laser ablation (PLA) of Zn plate in acetone. The beam of a Q-switched Nd:YAG laser of 1064 wavelength at 7ns pulse width and different fluencies was employed to produce nanoparticles. The ZnO nanoparticles were found to be hexagonal. The size distribution of generated nanoparticles is increased by increasing the laser fluence. The production rate of nanoparticles is increased with increasing the laser fluence. ZnO nanoparticles were formed with spherical shape. The bandgap energy of nanoparticles is calculated to be 3.59-3.89eV. In this range of ZnO nanoparticle size, photoluminescence spectrum exhibits two peaks due to bandgap transition and defect levels.