TiO2 powder was modified by LiF through hydrothermal treating of LiF and TiO2 mixed powders. The powders were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis spectrometry, X-ray diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The hydrothermally treated LiF-TiO2 powder has shown strong absorbability of organic dye methylene blue (MB). XRD and XPS results demonstrated that the existence of LiF crystals was the main reason for the improved absorbability of TiO2. Charge transfer between LiF and TiO2 which could cause obvious polarization at the interface of the two materials is considered to be the source of the remarkable enhancement of the large amount of MB absorption on the surface of TiO2. The LiF modified TiO2 could be used as functional material with good absorbability in the area of gas sensing, dye-sensitized solar cells and photocatalysts.