CO² capture，utilization，and storage （CCUS） can achieve a win-win situation of carbon emission reduction and oil production increase，and it is a key technology for the green and low-carbon transformation of the fossil energy industry. The petroleum and petrochemical industries have accelerated the large-scale application of CCUS technology after China proposed the goals of “peaking carbon emissions before 2030 and achieving carbon neutrality before 2060” in September 2020. It has gradually been revealed that CO² flooding has contradictions such as a low impact， short effective time，and rapid increase in the gas-oil ratio in the field practices of SINOPEC Shengli Oilfield and CNPC Jilin Oilfield. It is necessary to strengthen the optimization design of reservoir engineering further. This article systematically analyzed field practices of CO² flooding to enhance oil recovery in sandstone reservoirs in China and abroad and key issues in the optimization design of reservoir engineering，such as the matching between reservoir pressure maintenance level and miscible pressure，between well pattern direction and formation stress direction， between well spacing and reservoir permeability，and optimization of gas-water alternative displacement methods combined with the research results of the million-ton CCUS demonstration project in Shengli Oilfield. Then， the article summarized the latest progress in reservoir engineering research，such as reservoir pressure maintenance level during CO² flooding，well network，well spacing，and gaswater alternative displacement， and analyzed the increasing pressure method， well pattern， well spacing， and gas-water alternative displacement optimization design for high-pressure miscible flooding. Finally， it indicated that the research direction of CO² flooding reservoir engineering design should focus on the phase and flow laws of crude oil，CO²，and water in porous media under highpressure conditions， the synergistic mechanism of CO² flooding and storage，and the gas channeling mechanism of CO² flooding under complex reservoir conditions. This article provides technical support for large-scale CO² flooding in China.