In the advanced phase of CCUS(CO₂ capture, utilization and storage), a technique for increasing the CO₂ geological storage capacity using ammonia water was suggested. Ammonia water was injected into the reservoir, where it reacted with CO₂ to expand the storage volume. A high-temperature, high-pressure physical simulation device and core flooding apparatus was utilized to narrow down the experimental parameters for 20 MPa, 40 ~ 80 ℃, and an ammonia water concentration of 6% ~ 26%. The interaction between ammonia and CO₂ and ammonia's efficacy in amplifying CO₂ storage were clarified through the experiments. The results show that the amount of CO₂ absorbed by ammonia is proportional to the concentration of ammonia, and inversely proportional to the temperature. But ammonium bicarbonate crystals will be precipitated at low temperature, reducing the amount of CO₂ absorbed by ammonia. The absorption capacity of ammonia is negatively correlated with ammonia concentration, but had no obvious linear correlation with temperature. Saturated 6% ammonia water increases the CO₂ storage volume in cores by 7.5 times compared to saturated formation water. Moreover, with every 0.5 increase in core tortuosity, the CO₂ storage volume per unit rock pore volume in ammonia-enhanced storage increases by 200 mL, whereas that in formation water storage only rises by 11 mL. An innovative CO₂ storage model and conducts experimental research is presented for the first time, which provid a new approach and method for enhancing CO₂ geological storage in oil and gas field CCUS projects.