Abstract: Up to now, DC electric field EOR method is a new technology in the world.Test shows that the DC electric field can increase oil production, decrease water production and therefor, improve oil/water ratio. It also shows that the higher water-cut is, the better result can be received. The technology has significant effects for oil recovery at high and extra high water-cut stage. This paper describes how DC electric field enhances oil flow, in creases water injectivity and disposes formation plug. It also gives discussions on this mechanism.