Structural properties of zinc oxide (ZnO) nanoparticles and nanorings have been investigated by performing both equilibrium and nonequilibrium classical molecular dynamics simulations at various temperatures. An atomistic potential energy function has been used to represent the interactions among the atoms. It has been found that ZnO nanostructures undergo a structural change depending on temperature and different models. ZnO nanorings change into rod like structures with the effect of temperature. On the other hand, some of the ZnO nanoparticles transform into cubic like structures, whereas the others change to flower like structures with temperature.