We report the fabrication of single crystal kinked ZnO [001] and [100] nanowires (NWs). From the detailed morphology and microstructure analyzed by transmission electron microscopy, we discuss the growth characteristics, including nucleation and kinking, from a growth process point of view. We have discovered that the crystallographic property of the substrate surface played a critical role in determining the growth directions, which in turn determine the characteristics of single crystal kinking. A mechanism based on the unbalanced facet growth was proposed to explain the kinking of the single crystal kinked nanowires. Photoluminescence spectra confirm that the optical property of the ZnO NWs was not altered by the single crystal kinking.