The growth of zinc oxide (ZnO) nanostructures on Au-, Cu- and Zn-filled (111) and (100) porous silicons (PSs) has been investigated. The results indicate that the ZnO nanostructures grown on Au-filled (111) PS are possessed of rod-shapes with hexagonal end faces, those on the Cu-filled (100) or (111) PS are possessed of belt-shapes or rod-shapes, and those on the Zn-filled (100) or (111) PS are possessed of wire-shapes. The ZnO growth on the Au- and Cu-filled PS are mainly along c-axis orientation, while its growth on the Zn-filled PS are mainly along [] orientation, and it possesses a single crystal hexagonal structure without dislocations and stacking faults. In addition, the green emission intensity of the ZnO grown on Zn-filled PS caused by oxygen vacancies of the ZnO is weaker than that of the ZnO grown on Au (Cu)-filled PS,. It could be concluded that the ZnO grown on Zn-filled PS produces a better quality. After annealing in air, the positions of the green emission peaks do not vary, while the intensities are weakened