In the process of CO2 reinjection to improve gas reservoir recovery rate, due to its own characteristics and formation pressure difference, CO2 is prone to a large amount of filtration into the reservoir compared to other fluids. Therefore, it is necessary to study the filtration property of reinjecting CO2 into carbonate reservoirs. This article selects carbonate rock core of the Maokou Formation and conducts experimental research on CO2 filtration property using the core-CO2 filtration experimental device. The experiment simulated the environment around the well of reinjecting CO2 and studied the impact of filtration on injection by CO2. The effects of different temperatures and pressures on CO2 filtration rate were analyzed. The experimental results show that when CO2 is in a gaseous state, filtration rate of CO2 rises with the increase of experimental pressure, while the opposite is true when CO2 is in a supercritical state; Under supercritical conditions, the filtration rate of CO2 decreases with the increase of formation temperature. The group with the highest sensitivity to filtration rate is the group with a pressure of 10 MPa. When the temperature increases from 45 to 60 °C, the filtration rate decreases by 84%. The rate of change in filtration rate caused by unit pressure change is lower than that caused by unit temperature change. The research results further explore the CO2 filtration property and dominant factors in carbonate reservoirs, providing an experimental theoretical basis for studying the influencing factors of interaction between CO2 and rocks, and having certain guiding significance for CCUS-EGR technology research. This paper was prepared for presentation at the 2024 International Field Exploration and Development Conference in Xi’an, China, 12–14 September 2024.