Flower-like CuO nanostructures have been prepared via cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method. Here, CuCl2•2H2O was used as copper raw material, and sodium hydroxide was used as precipitate. The resulting CuO powders were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). X-ray diffraction (XRD) pattern exhibited the nanocrystalline nature with monoclinic structure for the as-synthesized nanostructures. FESEM images indicated that the flower-like CuO nanostructures are composed of many interconnected nanosheets in size of several micrometers in length and width and 60-80 nm in thickness. The possible formation mechanism of flower-like CuO nanostructures was discussed.