A two-step route is presented to dope Ga into ZnO nanowires and also fabricate heterostructures of Ga-doped ZnO nanowires on ZnO. The content of Ga in ZnO nanowires is about 7 at. % from energy-dispersive x-ray analysis. The single crystal Ga doped ZnO nanowires with the diameter of 40 nm and the length of 300–500 nm are well aligned on the ZnO bulk. The growth direction is along [001]. Raman scattering analysis shows that the doping of Ga into ZnO nanowires depresses Raman E1L mode of ZnO, manifesting that Ga sites in ZnO are Zn sites (GaZn). The formation mechanism of Zn1−xGaxO nanowires/ZnO heterostructures is proposed.