Zn and Cu were separately incorporated to the diamond powder and then the compacts were prepared under 5GPa, 1273K. The results showed that Zn was a good additive to prepare polycrystalline diamond by high-pressure and high-temperature (HPHT) because it could inhibit the graphitization of diamond. The element Zn left in the polycrystalline was in the form of ZnO. The photoluminescence spectroscopy showed that there were a series of sharp bands between 310 and 390nm when the excitation was above 200nm. However, the full width at half maximum of the diamond peaks mostly was below 0.5nm. The intensity of sharp band decreased with the decrease of excitation energy and then disappeared at last.