Abstract: In view of the problem that the effect of capillary pressure is uncertain and is often overlooked during CO2 displacement in low permeability reservoirs, the indoor experiment and numerical simulation analysis were combined to study the effect of capillary pressure in CO2 displacement in low permeability reservoirs. Based on long core indoor experiment under different CO2 displacement manners, a 1D numerical simulation model of CO2 flooding was built, and the effect of capillary pressure on the role of different CO2 displacement manners was analyzed through simulation. The research results show that, in low permeability reservoirs, the effect of capillary pressure in different CO2 displacement manners are not consistent. The displacement process is shown as dynamic power, but the displacement process after pressure buildup is shown as resistance. Therefore, in order to promote the reasonable and effective development of low permeability reservoirs, it is necessary to effectively identify the role of capillary pressure in CO2 flooding.