In this research, composite photocatalysts were found to have a superior photocatalytic performance. A simple hydrolytic method is used to synthesize the BiPO₄/Bi₄O₅I₂ composite, and this was confirmed by use of characterization methods. The oilfield pollutant of acrylamide was used to evaluate the photocatalytic activity. After ultraviolet visible (UV-Vis) light irradiation for 6 h, the BiPO₄/Bi₄O₅I₂ displayed an excellent photocatalytic performance which was better than using Bi₄O₅I₂ and BiPO₄ singly. The characterization data further demonstrated the remarkable photocatalytic activity of BiPO₄/Bi₄O₅I₂. The trapping experiments and ESR experiments verified the photocatalytic mechanism. The recycling experiments used the degradation of Rhodamine B (RhB) to investigate the stability and reusability of BiPO₄/Bi₄O₅I₂. This paper details a new approach for the synthesis of a BiPO₄/Bi₄O₅I₂ composite, which exhibited efficient photocatalytic activity, for use in the degradation of oilfield pollutants.