Bismuth oxychlorides have attracted much attention from the superior optical properties as photocatalysts to decompose organic pollutants under visible light especially with oxygen-rich status. Mechanochemical method was used to synthesize bismuth oxychlorides as a time-saving, environmentally friendly and efficient material preparation means in this research. As a kind of antibiotic, ciprofloxacin can make bacteria or viruses in the environment resistant to it, which seriously threatens human health and ecosystem. The mechanochemically synthesized BiOCl can effectively degrade the organic pollutant ciprofloxacin, while the oxygen-rich samples of Bi12O15Cl6 and Bi12O17Cl2 show higher photocatalytical capacity, attributable to the higher adsorption of the light in wider wavenumber and better depression of the recombination of photo-generated charge carriers. This study provides a new approach for the syntheses of bismuth oxychlorides with easy regulation in compositions such as atomic ratio of oxygen to chlorine and clarifies the potential application advantages of this photocatalyst. [GRAPHICS] .