Abstract: Black nanostructured BiOCl microspheres were directly synthesized by a hydrothermal method.The black ball-like BiOCl microspheres and black flower-like BiOCl microspheres were obtained using different surfactant.The color of the BiOCl microspheres turned from black to white when being annealed at 400 °C in air for 3 h and could be recovered to black by exposure to ultraviolet light for a few hours.The photocatalytic activity of both the black and the white BiOCl microspheres was characterized by the photo-degradation of methyl orange dye under visible light irradiation.The black ball-like nanostructure BiOCl displayed the best photocatalytic activity,compared with the white BiOCl and the black flower-like BiOCl.It can degrade the methyl orange dye to 20% within 70 min under visible light irradiation.The high activity of the BiOCl ball-like sphere may own to its special morphology,strong absorption in visible light range and the existence of oxygen vacancies.