Effects　of　ultraviolet　(UV)　light　illumination　on　the　corrosion　behavior,　surface　state,　and　activities　of　electro-deposited　micro-TiO2/Ni　and　nano-TiO2/Ni　composite　foils　in　3.5%　NaCl　solution　were　investigated　by　means　of　polarization　measurement,　electrochemical　impedance　spectra　(EIS),　electron　work　function　mapping　(EWF)　and　XPS　spectra　analysis　using　an　electrochemical　system,　the　atom　force　microscopy　(AFM)　and　X-ray　photoelectric　spectroscopy　(XPS),　respectively.　The　UV　light　illumination　resulted　in　a　considerable　decrease　in　corrosion　resistance　of　the　nano-TiO2/Ni　composite　foil　but　showed　much　less　effect　on　the　micro-TiO2/Ni　composite　foil.　Surface　state　analysis　demonstrated　that　the　UV　illumination　stimulated　the　nano-TiO2　semiconductor　with　elevated　conductivity　in　favor　of　passing　corrosion　current.　The　UV　illumination　increased　the　fraction　of　Ni2O3　component　in　formed　oxide　film　on　the　nano-TiO2/Ni　foil,　which　is　porous,　loose,　brittle　and　less　protective,　compared　to　the　naturally　formed　NiO　film　on　Ni.　The　changes　in　surface　state　were　responsible　for　variations　in　the　corrosion　behavior　of　micro-TiO2/Ni　and　nano-TiO2/Ni　composite　foils　caused　by　the　UV　light　illumination.