The photocatalytic degradation of Bisphenol-A (BPA) by the nanosheets Bi2O3 under visible light irradiation has been investigated experimentally and theoretically.The effects of the photocatalyst Bi2O3 on the degradation and mineralization have been examined by UV-visible absorption and total organic carbon (TOC) analysis.Bi2O3 plays an important role in degrading and mineralizing BPA finally to CO2 and H2O.The UV-visible absorption of BPA and the amount of TOC have been decreased obviously in 30 minutes.The intermediate products have been analyzed by HPLC and LC-MS,and three possible intermediates have been detected,which are m/z 151,m/z 133,and m/z 137.The DFT calculations were carried out by the hybrid B3LYP functional with double-zeta LanL2DZ basis set.We first treat the photocatalyst Bi2O3 as a reactant in the reaction,and realize the active sites molecularization to explore the photocatalysis mechanism on the level of molecule,finally five intermediates are obtained,three experimently detected by the LC-MS,as might be methyl phydroxybenzoate,4-isopropenylphenol,and p-hydroxybenzoic acid,respectively.The other two intermediates which were not detected by experiment are hydroquinone and 4-hydroxyacetophenone.A reasonable pathway of photocatalytic degradation of BPA by Bi2O3 is presented.