Nanometer-sized silicon oxide can be used in water flooding in oil development because of its super hydrophobic and oleophilic ability. In oil reservoir, these nanomaterials are usually physically adsorbed on the surface of sandstone and improve the wettability and water phase permeability. Therefore flow resistance is reduced and water adsorbing index is increased. Both experiment and application results show that nanometer silicon oxide is an excellent material used for water flooding, water injection pressure and ability of adsorping water in low permeability reservoir. The paper analysis the mechanism of increasing water adsorbing index and discuss the conditions for selecting water injection well.