BiOCOOH was prepared by solvothermal method, and the Bi/BiOCOOH composite photocatalyst was synthesized by in-situ reduction of BiOCOOH with NaBH₄ aqueous solution as reducing agent. The structure, morphology and optical properties of the prepared photocatalyst were characterized by XRD, FESEM, TEM, DRS and PL. The photocatalytic activity of Bi/BiOOCOOH composite photocatalyst was determined by the degradation of Rhodamine B. The influence of NaBH₄ dosage was investigated. The results indicate that the Rhodamine B can be thoroughly degraded in 50 min when the dosage of NaBH₄ is 25 mg. This can be ascribed to the SPR effect of Bi, which reduces the recombination rate of photogenerated electrons and holes and enhances the absorption of visible light.