Some small particles can be produced from TiO 2 by using photocatalytic reaction. These small particles have high oxidation ability and can be usedi n refrigeration equipments in order to sterilize and kill bacterium. The principle of TiO 2 photocatalysis and the actions of sterilizing and killing bcterium were introduced. It is explained that different structures of TiO 2 have different photocatalytic performances and clarify the ways of combining large band gap semiconductor with small band gap semiconductor and doping impurity to enhance TiO 2 photocatalytic efficiency. Some problems of TiO 2 photocatalysis and application prospects were put forward.