The average formation dip in Hailaer oilfield is more than 10°, and affected by gravity, the production wells in the middle and high position were not susceptible by water flooding. However, the water sensitivity of this reservoir is serious, so the conventional water flooding effect was poor. For dip-angle reservoir, gas injection in the high position can realize the effect of gravity flooding, which can effectively improve the development effect. In order to explore the adaptability of CO2 gravity flooding technology in Hailaer Oilfield, based on the laboratory experiment evaluation of CO2 gravity flooding for crude oil from this block, the influencing factors of gas gravity flooding were analyzed by numerical simulation method, and the reservoir development scheme of actual block were designed and optimized. The results of laboratory experiments showed that the recovery degree of CO2 gravity flooding could reach 41.96%, and the bidirectional gas–water flooding can increase by 7.62 percentages on this basis. The three-dimensional development mode of bidirectional gas–water flooding was optimized by the numerical simulation of the actual block reservoir. The results showed that the recovery degree of CO2 injected at the top and water injected on the side can be increased by 6.35 percentages compared with that of the water flooding development.