BiOBr/BiOCOOH p-n heterojunction photocatalysts were fabricated via a two-step solvothermal method. The photocatalytic performance of as-prepared heterojunctions was evaluated under visible light for the degradation of Levofloxacin. The composite samples exhibited significantly accelerative degradation rate compared to both pure catalysts (BiOBr and BiOCOOH). Besides, the apparent rate constant of the optimal sample for Levofloxacin degradation was 1.7 and 144.8 times higher than that of pure BiOBr and BiOCOOH. The improved activity can be attributed to the high charge separation efficiency. Furthermore, quenching experiment was also carried out. The results indicated that the photogenerated hole (h(+)) and superoxide radical (O-center dot(2)-) were the dominant reactive radicals responsible for the degradation of Levofloxacin. Cycling test also reveals that the sample owned good stability. In the end, a possible photocatalytic degradation mechanism was proposed. This work would provide a good example for the design and preparation of bismuth based p-n heterojunction composite photo catalysts with high visible-light-responsive performance for environment purification.