As a narrow band gap semiconductor, Bi₂WO₆ has great application potential in photo-degradation of organic pollutants, such as tetracycline. In present work, Bi₂WO₆ nanosheets were successfully synthesized by a hydrothermal method and the photo-degradation of tetracycline under visible light irradiation were investigated. XRD, FESEM, TEM and absorption spectra were used to characterize the structure and morphology of the material. It was found that when adding 50 mg Bi₂WO₆ nanosheets into 50 mL of tetracycline solution at pH=8, 85% tetracycline (50 mL, 50 mg/L) was photodegraded within 130 min. The photoelectron-chemical experiments and free radical capture experiments were performed to explore the photo-degradation mechanism. The results show that good photocatalytic performance of Bi₂WO₆ nanosheets are ascribed to the high electron density and photoelectron-hole separation efficiency.