BiOCl film with petal-like hierarchical structures is obtained by dipping bismuth film into the mixed solution of H2O2 and HCl. To obtain a high quality BiOCI film, a connecting layer of Chromium is deposited between the substrate and Bismuth film. The product is easy-synthesized, high productive, reusable and environment-friendly. The structural analysis indicates that the BiOCI film is composed by petals with smooth surfaces, and the nanopetals grow along the (101) directions. Raman spectroscopy shows that the film has a good stress-resist feature. The PL spectrum shows that the defect energy levels of BiOCI nanostructure contribute to the excellent photoactivity of degradation the rhodamine B (RhB) under visible-light irradiation (A > 420 nm). This photocatalyst can keep stable photoactivity after it has been reused for 6 rounds. All those properties ensure the photocatalyst a bright future in the application of the pollution treatment.