With a suitable growth condition using CVD method, 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. To our best knowledge, there is no report in growing ZnO nanostructures on in-situ synthesized ZnSe. The growth direction of ZnSe nanorods on a facet of a ZnSe grain is quiet uniform. The growth mechanism of the nanostructure will be discussed. Meanwhile, the photoluminescence of the nanostructures will be investigated.