The high-density single crystalline Ga-doped ZnO nanorods were grown on a glass substrate using the hydrothermal method. The average length and diameter of the nanorods were approximately 2.36 microm and 90 nm, respectively. The Ga-doped ZnO nanorods had hexagonal wurtzite structure and a sharp morphology. The morphology and structure of nanorods were characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy, when the growth temperature of the nanorods was 90 degrees C, which ensured high crystalline quality.