Cl-doped and undoped ZnO nanostructures with different percentages of chlorine (6% and 9%) were synthesized by a thermal evaporation method in a horizontal furnace. The undoped ZnO structures had a hexagonal shape with micro sizes, while the Cl-doped ZnO structures with 6% chlorine showed a hexagonal shape with sizes in nanometer range, and Cl-doped ZnO with 9% chlorine exhibited nanowall morphology with very thin walls. The results of X-ray diffraction patterns exhibited that structures of all products are hexagonal. Optical properties of the products were characterized by photoluminescence (PL) spectrometer. The PL spectra of the Cl-doped ZnO nanostructures indicated a wide peak at the visible region. In addition, the PL results showed that the chlorine caused a wider band gap for ZnO. Finally, the products were characterized by Raman spectrometer and the results of the Raman confirmed the PL results. In addition, the Raman spectroscopy results indicted a stress in structures of the Cl-doped ZnO nanostructures.