A hierarchical polygon prismatic Zn-ZnO core-shell structure was grown on silicon by combining liquid-solution colloidals together with the vapor-gas growth process. Zn colloidals with a diameter of 5-10 nm synthesized from Zn(ClO4)2 precursor solution were used as nucleation seeds for the growth of Zn polygon prismatic nanocrystals. Depending on carrier gas and annealing conditions, the polygon prismatic Zn crystals having morphology from hollow to dense configuration can be manipulated. Moreover, after prolonged thermal treatment at 300-400 °C, polygon prismatic hollow ZnO-Zn crystals with a dimension from nanometer to micrometer can be obtained. The room-temperature photoluminescence spectra show that the hollow ZnO-Zn crystals have a weak ultraviolet (UV) emission at 380 nm and a strong green emission at 500 nm. However, the intensity of the UV emission can be improved by postannealing the Zn-ZnO core-shell structure in an oxygen atmosphere to form hollow ZnO crystals.