Abstract: CO₂ flooding and storage not only has economic effect, but also plays a role in environmental protection. Calculating CO₂ storage potential is of great significance to the design of oil reservoir development scheme and the safe storage. Existing potential calculation methods mainly estimate CO₂ static storage potential roughly without considering actual oilfield production situations. To this end, this paper put forward a new method to calculate the dynamic storage potential of CO₂ flooding based on compositional flash calculation. This method is based on compositional flash calculation while considering the actual oilfield production situations and the storage mechanisms of CO₂ flooding. It can be used to calculate dissolved CO₂, trapped CO₂, free CO₂ and total CO₂ storage potential. It is indicated that with the increase of storage time, free CO₂ will transform into trapped CO₂ and dissolved CO₂. As for the waterflooding oil reservoirs, the formation water content is high, so the dissolution of CO₂ in formation water shall not be neglected. The CO₂ flooding dynamic storage potential calculation method based on compositional flash calculation is simple, practical and in line with the actual production and it can be used to calculate the dynamic storage potential of different types of oil reservoirs under different development modes.