An InYO3 photocatalyst was prepared through a precipitation method and used for the degradation of molasses fermentation wastewater.The InYO3 photocatalyst characterized by X-ray diffraction (XRD),UV-Vis diffuse reflectance spectroscopy,surface area and porosimetry.Energy band structures and density of states were achieved using the Cambridge Serial Total Energy package (CASTEP).The results indicated that the photodegradation of molasses fermentation wastewater was significantly enhanced in the presence of InYO3 when compared with PbWO4.The calcination temperature was found to have a significant effect on the photocatalytic activity of InYO3.Specifically,InYO3 calcined at 700℃ had a considerably larger surface area and lower reflectance intensity and showed higher photocatalytic activity.The mathematical simulation results indicated that InYO3 is a direct band gap semiconductor,and its conduction band is composed of In 5p and Y 4d orbitals,whereas its valence band is composed of O 2p and In 5s orbitals.