The invention relates to an oil-field largest swept volume chemical-flooding oil production method, which is applied to the technical field of oil production in oil fields. The method is applicable to all reservoirs which can be exploited by water flooding but are not exploited by water flooding. When oil is exploited, the self energy of the strata of a reservoir is first utilized to carry out flowing production or swabbing production; when an oil field adopting flowing production or swabbing production reaches the economic benefit limit of production, flowing production or swabbing production is ended, subsequent water-flooding production is not carried out any more, but chemical flooding injecting surfactant as main agent is directly adopted to intensify oil production. The method has the following advantages that: at the moment, the swept volume of the displacement of the chemical displacing fluid is the largest, which is best favorable for the exertion of the oil-washing effect ofthe surfactant, and thereby the yield of oil production can be increased to the max.