<p>The injection of gas into coal seams to improve gas extraction is a key technological approach for gas drainage. Examining the substitution of coal seam gas with methane/carbon dioxide (CH₄/CO₂) mixed gas, this study explored how moisture affects the displacement of CH₄ by CO₂ in coal, thereby enhancing gas extraction efficiency. This study combined molecular dynamics simulation software with laboratory experiments, utilizing Materials Studio, to elucidate how varying moisture in coal affects adsorption characteristics of CH₄/CO₂ mixed gas. Isothermal adsorption experiments were performed with single-component gases and binary mixed gases. A molecular model of moisture-containing coal was developed, and Materials Studio software conducted numerical simulations for calculations. Results were integrated with laboratory experiments and fitted to the Langmuir equation. The study determined how varying moisture content in coal affects adsorption characteristics of mixed gas. The results indicated that adsorption constants for CO₂ drop more than those for CH₄ under the same circumstances; moisture has a stronger effect on CO₂ adsorption. The coal showed a non-linear decrease in total adsorbed amount as well as CH₄ and CO₂ adsorption. The adsorption levels in coal samples fall quickly at first before stabilizing as the moisture content rises.</p>