In this study, we synthesized various dimensionalities of ZnO nanowires using the Ti grid-assisted chemical vapor deposition process. Energy dispersive X-ray spectroscopic mapping technique accompanied with a lattice diffusion model was used to characterize the growth mechanism. A diffusion ratio γ, defined by short-circuit and lattice diffusion activation energies, was obtained to describe the growth mechanism of ZnO nanowires. The tunable dimensionalities of ZnO nanowires allow us to modify the morphology of ZnO nanocrystals by developing well-controlled potential applications.