The ZnO nanorods grown on in-situ synthesized ZnSe grains through the chemical vapour deposition method are reported here for the first time. With a suitable growth condition, single crystal ZnO nanorods grow on the well-defined bounded facets of the random shape ZnSe grains using Zn and Se powders without any metal catalyst. The growth direction of ZnSe nanorods on a facet of a ZnSe grain is quite uniform. The synthesis mechanism of the ZnO nanorods on the ZnSe grains is proposed. The effects of the Se powder usage on the ZnO-ZnSe products and the photoluminescence of the products are investigated.