Abstract: In order to efficiently make use of visible light and enhance photocatalytic activity,the rutile crystal TiO₂ catalysts which could utilize visible light were obtained by heat-treated method.The damage of BSA under the visible light irradiation in the presence of heat-treated anatase TiO₂ was investigated by means of UV-Vis and fluorescence spectroscopies.The photocatalytic activity of the heat-treated TiO₂ was compared with that of the untreated one.In addition,the influences of irradiation time,TiO₂ addition dose and irradiation power on the damage of BSA molecule were studied.The results show that the damage of BSA under the visible light irradiation was achieved in the presence of heat-treated anatase TiO₂.The photocatalytic activity of heat-treated TiO₂ was also better than that of the untreated one.The obvious hyperchromic effect in UV-Vis spectra and the fluorescence quenching in fluorescence spectra were both observed,which resulted from the exposure of aromatic heterocycle residues of tryptophane and tyrosine.Moreover,the damage degree of tyrosine residues was greater than tryptophan residues,which was proved with synchronous fluorescence spectra.For a BSA solution of 1.0×10^-5 mol/L at 25℃,the damage of BSA was aggravated with the increase of the irradiation time,TiO₂ addition dose and the irradiation power.They are of significance to the study on the application of scavenger and inactivator for some virus.