Abstract: The YFeO₃ powder of different crystallographic structures was prepared by using the sol-gel method. The products were characterized by X-ray diffraction (XRD)， differential thermal analysis-thermogravimetric (DTA-TG) analysis， special surface area analysis (the BET method)， and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The photocatalytic activities of the samples were evaluated by using the photocatalytic degradation of methylene blue (MB) under visible light. The results show when the temperature increases from 973K to 1073K， the crystallographic structure of the YFeO₃ power changes from hexagonal to orthorhombic phase. Compared with orthorhombic phase of the YFeO₃， the hexagonal phase presents a relatively larger specific surface area， a wider absorption edge， a narrower bandgap width， a more negative valence position， and a more positive conduction band position. Meanwhile， the performance of photocatalytic degradation of the MB is better.

Key words: sol-gel method, YFeO₃, powder, visible light catalysis, methylene blue( MB)