Abstract: Gas injection pressure is an important technical parameter of gas injection for gas drainage in coal seam. In order to study the effects of CO₂ gas injection pressure on the changes of CH₄ production and CO₂ storage characteristics in the process of CO₂ displacing CH₄, the self-built CO₂ displacing CH₄ experimental system was used to carry out the CO₂ displacing CH₄ with different CO₂ gas injection pressures (0.6 MPa, 0.8 MPa and 1.0 MPa). The changes of CH₄ flow rate, CO₂ storage, pore pressure, replacement volume ratio, CH₄ production rate and CO₂ storage rate with gas injection pressure during displacement were quantitatively analyzed. The experimental results show that in the low pressure range of 0.6-1.0 MPa tested, increasing the CO₂ injection pressure is conducive to producing more CH₄ and storing more CO₂. The greater the gas injection pressure, the greater the CO₂ storage capacity, replacement volume ratio, CH₄ production rate and CO₂ storage rate, and the shorter the CO₂ breakthrough time and the time required to reach the new adsorption saturation state. When the gas injection pressure was 0.6 MPa, 0.8 MPa, and 1.0 MPa, the CO₂ storage capacity at the end of the experiment was 16.48 cm³/g, 16.74 cm³/g, and 19.91 cm³/g, respectively, and the production rate of CH₄ was 76.98%, 78.94%, and 81.27%. The CO₂ storage rate was 72.76%, 87.80%, and 86.11%, and the replacement volume ratio was 2.98, 2.90, and 3.33, respectively, and the breakthrough time was 76.00 min, 74.00 min, and 64.83 min, respectively. When the gas injection pressure increased from 0.6 MPa to 1.0 MPa, the CO₂ storage capacity and CH₄ production rate increased by 20.81% and 4.29%, respectively. With the increase of gas injection time, the flow rate of CH₄ at the outlet increases slowly, decreases gradually and tends to be stable, and the pore pressure increases gradually and tends to be stable (gradually approaching the CO₂ gas injection pressure). The whole gas injection displacement process can be divided into three stages, and the dominant control effects are CO₂ driving away free CH₄, CH₄ self-desorption and displacement, and CO₂ dilution carrying CH₄. In the field application process, relevant process parameters should be reasonably adjusted and optimized according to the specific characteristics of each stage, so as to make the technology of CO₂ injection for CH₄ displacement and CO₂ geological storage is more efficient.