La-doped TiO2 nanopowders were synthesized via sol-gel process,and X-ray diffraction(XRD),UV-visble absorption spectra techniques were applied to investigated thes phase structure and spectrum properties as-synthesized samples.The influence of La3+ doping on the structure and phase transformation behaviors of anatase to rutile TiO2 powders was investigated by means of XRD.UV-vis adsorption spectroscopy revealed that La-doped TiO2 has a strong a adsorption band and the absorption edge were red-shifted compartion with pure TiO2.The experiment results of photocatalytic decomposition of methyl-organge indicated that La-doping restrained the transformation of anatase to rutile and growth of grain.Therefore,La-doping improved the TiO2 photocatalytic activity in photodegradation of methyl-organge.In addition,experiments also illustrate that the catalyst has good activity of decolor rate of Yan’an cigarette factory wastewater.