Abstract: The combination of ultrasound (US) and ultraviolet irradiation (UV) with TiO₂ nanoparticles as the photocatalyst was used to degrade poly (vinyl alcohol)(PVA) in aqueous solution.US/UV/TiO₂ technique was considerably more effective than US or UV alone,and ultrasound and ultraviolet light exhibited synergistic effect.The sonophotocatalytic activity of rutile TiO₂ particles was obviously higher than that of anatase TiO₂ particles.The degradation rate of PVA is inversely proportional to the initial PVA concentration.The results show that it is more effective for PVA to be degraded under acidic or basic condition.The order of the reaction rates at different pH was pH 8.5 >pH 4.5 >pH 5.5 >pH 7.0.The sonophotocatalytic degradation of PVA in the presence of nano anatase TiO₂ catalyst followed a pseudo first-order kinetics.The reaction rate constant was 0.037 min^-1.The degradation ratio of PVA reached almost 100.0% within 80 min under the experimental conditions of 40 kHz ultrasonic frequency,1.0 g/L rutile TiO₂ catalyst,pH=5.5,and 30℃ temperature at an initial PVA concentration of 90 mg/L.GC,DTG and XPS results showed that the intermediates containing C-O,O-C=O groups were formed during the degradation reaction.The PVA finally mineralized to CO₂ and H₂O.