Abstract: Pure BiOBr and BiOI nanopowders were first synthesized by precipitation method. BiOBr main photocatalyst and BiOI cocatalyst with different contents were mixed and grinded. After grinding, the composite powder was calcined at different temperatures. The produced BiOI/BiOBr hetero-structured photocatalysts (BiOI mass fraction content: 1%, 2%, 4%, 8%) were characterized by N₂-physical adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier translation infrared spectroscopy (FT-IR), and UV-Vis diffuse reflectance spectroscopy (DRS) and photoelectrochemical measurements. Acid orange Ⅱ dye was selected as degradation target pollutant under visible light irradiation. The effects of BiOI coupling concentration and calcination temperature on the photocatalytic performance were investigated. The results show that the BiOI/BiOBr composite photocatalyst with 4% mass fraction of BiOI and calcination at 400 ℃ show about 0.7 and 0.9 times of increasement in degradation rate compared to pure BiOBr and BiOI, respectively. Coupling of BiOI cocatalyst promoted the visible light absorption. Moreover, the formation of BiOI/BiOBr hetero-structure could restrain the recombination rate of photogenerated electrons (e^-) and holes (h⁺). These two reasons could mainly account for the boosting of photocatalytic activity.