Flower-like copper monosulfide (CuS) hierarchical nanostructures composed of nanoplates were successfully synthesized by means of a simple solvothermal process, using CuCl2·2H2O as Cu-precursor, CS2 as S-source and ethylene glycol (C2H6O2) as the solvent. The morphology and structure of the product were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The optical properties of the copper monosulfide hierarchical nanostructures were investigated by UV-visible absorption spectra. In addition, the photocatalytic activity of the flower-like CuS hierarchical nanostructures were evaluated by the degradation of methyl orange solution under natural light. Results demonstrate that the as-prepared flower-like CuS hierarchical nanostructures possess high photocatalytic performance, the degradation rate is up to 100% after 90 min degradation under the irradiation of natural light, which is much higher than bulk CuS powder. The formation mechanism of flower-like CuS hierarchical nanostructures was preliminarily analysed, alss.