Flow mechanisms of multi-phase multi-component of CO2-crude oil system in porous media are very important for displacement process for CO2 flooding, enhanced oil recovery and even geology sequestration of CO2, etc. Phase behavior and percolation characteristics of multi-phase multi-component of CO2-crude oil system in porous media were studied by slim tube test, multi-contact test and numerical model considering mass transport. The results showed that CO2 flooding can vaporize not only the light hydrocarbons less than carbon 11, but even the heavy hydrocarbon components such as carbon 32. The displacement combined vaporizing and condensing process, and the miscible zone was just near the gas displacement front. Higher temperature and higher contents of N2 and CH4, larger the minimum miscibility pressure (MMP) was.