The surface modification of titanium dioxide (TiO2), which can be easily attained by a simple addition of ascorbic acid (AA) to aqueous TiO2 suspensions, affects the photodegradation. Surface modification results in the formation of a colored surface complex that causes red shift in the absorption threshold of TiO2. Photodegradable polypropylene (PP) composite films were prepared by embedding AA modified nano TiO2 into the PP matrix (PP/(AA/TiO2)). The photocatalytic degradation behavior of PP/(AA/TiO2) composite film under UV light irradiation as investigated and compared with those of the PP/TiO2 and neat PP films, with the aid of UV-Vis spectroscopy, Fourier Transform Infrared spectroscopy, weight loss monitoring, tensile test and scanning electron microscopy. The degradation rate of the PP/(AA/TiO2) composite films is three times higher than that of PP/TiO2 film and six times higher than that of neat PP film. In addition, the FTIR spectra show that the intensity of the peak of carbonyl group for neat PP is much lower than that of the composite film.