Abstract: In this paper, triangular and hexagonal symmetry ZnO branching structures were synthesized by thermal evaporation method. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) to obtain the structural information. The trunk of ZnO branching nanostructures grows along0001 direction. The crystalline directions of the triangular symmetry ZnO are2110,1210 and1120, while those of the hexagon symmetry ZnO are. The formation mechanism of ZnO branching structures is presented based on HRTEM characterization and surface energy analysis. The optical properties of ZnO branching nanostructure were studied by UV-vis absorption spectrum and Photoluminescence (PL) spectrum. The band-edge emission at 3.23 eV(triangular) and 3.24 eV(hexagonal) are found to be red shift comparing with that of bulk ZnO.