According to the oxidation behavior of the alloys having Zn and Mg, the low specific gravity of Mg resulted in the AZD6244 of Mg toward the outmost layer of molten metal, which led to the oxidation of Mg on the outmost surface. Then, tensile stress developed at the interface due to the volume difference between the molten metal and the oxide layer. The tensile stress made microchannels inside the oxide layer. Then, Zn, which was in the interior of the molten metal because of its high specific gravity, was evaporated through the microchannels from the interior of the molten metal to the surface of the oxide layer. The evaporated Zn was oxidized on the oxide layer . Thus, Mg did not react with Zn, but it did affect the oxidation behavior of Zn and the oxygen concentration during the growth of ZnO nanostructures. It has been reported that oxygen concentration is the critical parameter for modifying the morphology of ZnO nanostructures . In the present work, the ratio of Mg to Zn had an effect on the oxygen concentration, which resulted in the fabrication of ZnO nanostructures with different morphologies.