Injecting CO2into deep coal seams is key to successful CO2sequestration and enhancing coalbed methane production; however, various underground conditions influence the process. In this study, experiments were conducted to determine optimum conditions for replacing CH4with CO2injection at different temperatures (20, 30, and 40 °C), pressures (2, 3, and 4 MPa), and supercritical conditions (35, 45, and 55 °C). The results show that the proportion of adsorbed CH4decreased with decreasing desorption pressure but increased with increasing temperature. Low temperatures were relatively more conducive to replacing CO2with CH4. With an increase in the original CH4adsorption equilibrium pressure, there was an increase in CH4adsorbed proportion but a decrease in CO2adsorbed concentration. Desorption rates showed that the replacement effect was superior under low original reservoir pressures. Under supercritical conditions, the maximum Gibbs adsorption volume for CO2was obtained, and the absolute adsorption volume conformed to classical Langmuir curves. During the replacement process, the percentage of adsorbed CO2increased with increasing temperature, while the concentration of CH4decreased. The CH4desorption rate was higher, and the displacement effect was superior when temperature and pressure were close to the critical condition within the supercritical range.