In order to study the impact of injection parameter during gas-assisted gravity driving in conglomerate reservoir. The gas-assisted gravity driving experiment under reservoir dip was carried out by using full diameter conglomerate core. Based on the results of laboratory experiments, homogeneous and heterogeneous numerical simulation model of gas-assisted gravity driving was established to study the impact of injection parameters on oil recovery factor. The results show that the oil recovery factor of 0.63 PV injection can reach 47.6% when the angle is 10°and the injection speed is 0.02 cm3/min. After 0.55 PV, the gas-oil ratio reaches 5000 m3/m3, and the subsequent oil recovery factor tends to be stable. In the numerical simulation homogeneous model, the effect of gas channeling is little. Because the sweep is relatively uniform, it is difficult to reflect the advantages of gravity flooding, and the difference of oil recovery factor is little in different inclination angles. Using heterogeneous numerical model, the displacement efficiency increases significantly with the increase of inclination angle. Compared with plane flooding(0° inclination), the oil recovery factor of gravity flooding (30°inclination) is increased by 7.6%. for immiscible displacement process of gravity flooding, the pressure has little influence on the oil recovery factor. When the injection speed is less than 0.1 cm3/min, the oil recovery factor shows an obvious upward trend with the increase of the injection speed. When the injection speed is greater than 0.1 cm3/min, the gas-oil ratio during the flooding process reaches 5000 m3/m3 rapidly, and the oil recovery factor decreases. Compared with the single CO2-assisted gravity driving, the injection mode with pre-CO2 and subsequent N2 can increase the oil recovery by 2.6%, and has higher economic benefits.