Based on a large quantity of PVT analysis data of the Shengli oil field and after analyzing the impact factors, this paper puts forward a method which accords with the oil accumulation law.On the one hand,this method formulates experiential formulas using multiple factors,including depth,ground oil density,temperature,pressure,and so on.These factors can be obtained by tests.On the other hand,the residue is acquired by analogy to offset the impact of other factors such as the underground oil-gas ratio,saturation pressure which can not be obtained by tests.Thus,the precision of the crude oil volume factor is improved.