Abstract: The TiO2 nanopowders with different Yb doping amount were prepared by a facile sol-gel method.The samples were characterized by XRD,XPS,TEM,FT-IR,UV-Vis,PL and Nano-sizer nano particle size analyzer,etc.The influence of Yb-doping on structure and visible photocatalytic activity of mixed phase TiO2 was evaluated by photocatalytic degradation of methylene blue (MB) under the irradiation of fluorescent lamp.The results show that ytterbium appeared two kinds of Yb3+ and Yb2+ valence state on the surface of TiO2.Ytterbium doping can restrain the phase transfer from anatase to rutile,prevent the grain growth,and increase the surface hydroxyl content.Appropriate amount of Yb doping and the proportions of rutile and anatase mixed phase can effectively inhibit the recombination of photogenerated electron and hole,expand the wavelength range of absorption spectrum,and improve the photocatalytic performance of TiO2.Meanwhile,the photocatalytic activity of the Yb-TiO2 samples was the best under the irradiation of fluorescent light when the sintered temperature t=500 ℃ and n(Yb)∶n(Ti)=0.009,it was 95.2% within 6h and significantly higher than 56.4% of pure TiO2 under the same experimental conditions.