Abstract: Nanometer Polysilicon is one of the method to resolve the problem that injected pressure is high in a long time, water flooding volume is low, the difference of injected pressure of each well is very large in water flooding of low permeability oil field. Nanometer Polysilicon can change the wettability of rock, enhance relative permeability of water, at the same time, because of its stronger hydrophobility, reduce significantly the flow resistant of water flooding through core driving experiment and micro-driving test. The core driving experiment and full size field test prove that it is important for success of construction to select well. Its best economic profit can be proved through economic evaluation.