Abstract: CO_2 is one of the main greenhouse gases emitted by human production and living activities,which is recognized as the main cause of global climate change. CCUS technology is an important way to achieve deep emission reduction of CO_2 and mitigation of climate change. Among them,CO_2-EOR technology has broad prospects. As an ideal place for carbon storage,oil reservoirs can not only achieve long-term effective storage of CO_2,but also enhance oil recovery and achieve win-win of economic and social benefits. Determining the carbon sequestration potential of the target reservoir is of great significance for the large-scale implementation of CO_2-EOR technology. Nowadays,there are many methods to evaluate the storage potential of CO_2-EOR,but they can only be used for specific reservoirs and lack of standard universal methods. The mechanism of CO_2-EOR and sequestration was discussed,and the evaluation formula of CO_2-EOR storage potential proposed by domestic and foreign authoritative institutions was summarized in this paper. The universality of the method was demonstrated in detail through the analysis of examples,and the next step of accurately evaluating the carbon sequestration potential in the process of CO_2-EOR was prospected. During CO_2 flooding,oil recovery is enhanced by expanding oil volume,reducing crude oil viscosity,improving oil-water mobility ratio,extracting light components and miscible effect,while CO_2 storage depends on four mechanisms: structural trapping,residual trapping,solubility trapping and mineral trapping. The two concepts are different. At present,there are four authoritative and widely used evaluation methods of CO_2 storage potential: US-DOE,CSLF,USGS and RIPED & CUP method. Among them,US-DOE and USGS methods are estimation methods based on volume balance theory,which rely on storage efficiency and estimate the capacity of CO_2 storage through the combination of a variety of storage mechanisms. The CSLF method is based on the material balance theory,and the estimated results are consistent with the resource reserve pyramid,but the mechanism of solubility storage is not taken into account. RIPED & CUP method is actually an improved version of CSLF method,the dissolution of CO_2 in formation fluid is considered in this method,which makes the calculation formula more suitable for the reality of reservoirs in China,but it is difficult to determine the oil recovery in each stage. Therefore,in order to ensure the accuracy of the estimated results,the most appropriate evaluation method should be selected according to the geological characteristics of the reservoirs. Besides,for evaluating carbon sequestration potential more accurately,the next step should be carried out from the aspects of defining the reservoir development strategy,considering the lag effect,using field data for correction and strengthening safety risk assessment.