CO

2

flooding is a promising way to improve the crude oil recovery ratio. CO

2

could not only dissolve in crude oil

but also replace some light hydrocarbons or intermediate hydrocarbons in crude oil. So the composition has great influence on the component mass transfer and minimum miscible pressure of the CO

2

miscible flooding. Therefore

the influence of the quantitative characterization

of crude oil composition on the minimum miscible pressure of the CO

2

miscible flooding has engineering significance for the reservoir screening. Taking the original formation fluid of a certain oilfield in China as the research object

we analyzed the multistage contact miscibility mechanism. Meanwhile

we used the Winprop module in CMG to carried out the phase simulation of experimental data. The results show that the minimum miscible pressure between CO

2

and crude oil is proportional to the molar composition of N

2

C

1

and C

11+

and inversely proportional to that of C

2

C

10

. While the mixing of the CO

2

and reservoir fluids needs higher reservoir pressure than minimum miscible pressure. It requires that when screening reservoirs with CO

2

flooding

we should try to consider the reservoir with high mole content of C

2

C

10

and low mole content of C

24

. It has great guiding significance for miscible displacement design and miscible phase prediction.