The ZnO nanocombs have been successfully synthesized on Si (111) substrates with different substrate placed conditions by thermal evaporation method. The XRD, SEM, specrophotometer and fieldemission testing device are used to investigate the morphology, structure, photoluminescence and field emission properties of the ZnO nanocombs. XRD results indicates that both of the two samples under different substrate placed conditions(A:horizontal and B:vertical)belong to polycrystalline hexagonal structure. SEM results show that both of the two samples have nanocomb structure, but the size and the surface morphology of the nanocombs change with the different substrates placed conditions. The nanocombs in sample B are smaller and uniform. The room temperature photoluminescence(PL) spectra results show that the UV emission peak of the sample B appears blueshift in comparison to that in sample A, and the ratio of the UV emission peak to the visible emission peak in sample B is larger, indicating the high crystallization quality. Besides, The field emission test results show that the field emission of the both two samples conduct through the electronic tunnel effect, and the field emission performance of sample B is better.