To　investigate　the　photo-induced　hydrophilicity　of　TiO2　films　and　its　durability,　a　series　of　TiO2　films　containing　polyethylene　glycol　(PEG)　2000　with　different　contents　are　prepared.　The　photo-induced　hydrophilicity　of　the　films　is　investigated　by　recording　the　water-droplet　contact　angle　on　the　films＇　surface　under　UV　irradiation,　and　the　hydrophilicity　durability　is　monitored　under　dark　storage　conditions.　The　photo-induced　hydrophilicity　of　TiO2　films　and　its　hydrophilicity　durability　are　enhanced　by　introducing　2.0%　(w)　of　PEG　into　the　TiO2　sol.　From　Fourier　transform　infrared　(FTIR)　spectra　and　ultraviolet-visible　diffuse　reflection　spectra　(UV-Vis　DRS),　we　infer　that　PEG　acts　as　an　electron　donor　to　scavenge　the　photo-generated　holes　in　TiO2　and　promotes　the　formation　of　Ti3+　sites,　which　are　induced　by　the　Ti4+　sites　accepting　the　photo-generated　electrons　of　TiO2.　This　promotes　the　formation　of　hydrophilic　sites　(the　surface　hydroxyl　species).　Compared　with　the　pure　TiO2　film,　the　Ti3+　sites　in　the　TiO2/PEG　films　are　more　stable,　which　prolongs　the　hydrophilicity　of　TiO2　films　under　dark　conditions.　This　study　is　significant　for　the　application　of　TiO2　as　a　self-cleaning　material,　and　is　also　a　facile　approach　to　investigate　the　transient　behaviors　of　TiO2　under　UV　irradiation.