ZnSe sub-microstructures with different morphologies, sizes, and microstructures were synthesized by a modified vapor deposition method using CdSe nanocrystals (NCs) as the seeds. On the basis of the appearance of the as-synthesized products, we show that the substrate temperature and CdSe NCs are the critical factors for controlling the size and the structure of various ZnSe sub-micro structures. By manipulating the growth driving force (i.e., the degree of supersaturation), the morphology of the ZnSe crystals can be varied sequentially from nanobelts to meso-scale rods to wires/branched wires. Their morphologies and structures were characterized by X-ray spectroscopy, Raman spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The nanobelts grew along the [01-10] direction, whereas the meso-scale rods and wires grew along [0001]. Cathodoluminescence properties and growth mechanisms of these ZnSe structures are also discussed. The present results suggest that the simple method might be useful for the synthesis of other semiconductor nanostructures with manipulated morphologies to meet the growing demands of nanoscale science and technology.