Abstract: BiOBr/ATP composite photocatalysts were prepared in one step by wet mechanochemical synthesis, and the microstructure and morphology of the prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), infrared spectroscopy (FT-IR) and X-ray spectroscopy (XPS). And degradation activity of the catalysts were evaluated by photocatalytic degradation of tetracycline under visible light irradiation, and its performance and mechanism for the degradation of tetracycline antibiotics was investigated. The results showed that an intercalation structure was formed between the bumpy clay rod crystals (ATP) and bismuth oxybromide (BiOBr) nanosheets, and the photocatalytic effect of the composites was optimal at a mass fraction of ATP of 5%, with the tetracycline degradation rate reaching 88.23%. The main role was hypothesized to be (·O²⁻) by free radical inhibition experiments, and a possible mechanism of tetracycline degradation was proposed. According to the active species capture experiments, ·O²⁻ and ·OH were the major active species, and h⁺ and e⁻ were the minor active species. The transient photocurrent test showed that the photocurrent enhancement of BiOBr/ATP composite photocatalyst was 1.24 times higher than that of BiOBr.