Abstract: In order to overcome the difficulty of gas mining when coal mining depth increased, the adsorption and diffusion laws of CO₂ molecules at different temperatures and pressures were simulated by using the simulation software Materials Studio; the relationship between CO₂ mean square displacement and time was simulated based on molecular dynamics. The results showed that in the isothermal adsorption curves of 15 ℃, 25 ℃, 30 ℃ and 35 ℃, the adsorption capacity of CO₂ decreased gradually when temperature increased. It showed that CO₂ was conducive to geological storage at low temperatures; the values of self-diffusion coefficient, corrected diffusion coefficient and transfer diffusion coefficient of CO₂ in coal increased when temperature and pressure increased. The maximum value was reached at 35 ℃ and 3.5 MPa.