Abstract: In order to maintain the energy of shale oil reservoirs in northern Jiangsu Province, reduce the decline rate of production, and improve the recovery rate of shale oil reservoirs, the study on CO₂ high pressure quality exchange technology of shale oil in northern Jiangsu Province were carried out. The effects of CO₂ injection pressure and soaking time on crude oil recovery percent and CO₂ injection rate on crude oil recovery factor were analyzed by using shale oil reservoir cores in northern Jiangsu Province for laboratory experiments. Numerical simulation software was used to optimize the injection time, injection volume, injection rate, and shut-in time of Well SD1J. A field test of high pressure quality exchange technology with a super large volume of CO₂ was carried out in Well SD1J. After the measure implementation, the well produced oil normally. The daily fluid production decreased from 38.6 t/d to 30.3 t/d, and the daily oil production increased from 14.0 t/d to 29.2 t/d. The water content decreased from 63.8% to 3.5%. The results show that CO₂ high pressure quality exchange technology can increase the formation energy of shale oil reservoirs and reduce the decline rate of production, which provides new technical support for improving the development effect of shale oil reservoirs.