The　two-phase　seepage　fluid　(i.e.,　air　and　water)　behaviors　in　undisturbed　granite　residual　soil　(U-GRS)　have　not　been　comprehensively　studied　due　to　a　lack　of　accurate　and　representative　models　of　its　internal　pore　structure.　By　leveraging　X-ray　computed　tomography　(CT)　along　with　the　lattice　Boltzmann　method　(LBM)　enhanced　by　the　Shan-Chen　model,　this　study　simulates　the　impact　of　internal　pore　characteristics　of　U-GRS　on　the　water-gas　two-phase　seepage　flow　behaviors.　Our　findings　reveal　that　the　fluid　demonstrates　a　preference　for　larger　and　straighter　channels　for　seepage,　and　as　seepage　progresses,　the　volume　fraction　of　the　water/gas　phases　exhibits　an　initial　increase/decrease　trend,　eventually　stabilizing.　The　results　show　the　dependence　of　two-phase　seepage　velocity　on　porosity,　while　the　local　seepage　velocity　is　influenced　by　the　distribution　and　complexity　of　the　pore　structure.　This　emphasizes　the　need　to　consider　pore　distribution　and　connectivity　when　studying　two-phase　flow　in　undisturbed　soil.　It　is　observed　that　the　residual　gas　phase　persists　within　the　pore　space,　primarily　localized　at　the　pore　margins　and　dead　spaces.　Furthermore,　the　study　identifies　that　hydrophobic　walls　repel　adjacent　fluids,　thereby　accelerating　fluid　movement,　whereas　hydrophilic　walls　attract　fluids,　inducing　a　viscous　effect　that　decelerates　fluid　flow.　Consequently,　the　two-phase　flow　rate　is　found　to　increase　with　then-enhanced　hydrophobicity.　The　apex　of　the　water-phase　volume　fraction　is　observed　under　hydrophobic　wall　conditions,　reaching　up　to　96.40%,　with　the　residual　gas-phase　constituting　3.60%.　The　hydrophilic　wall　retains　more　residual　gas-phase　volume　fraction　than　the　neutral　wall,　followed　by　the　hydrophobic　wall.　Conclusively,　the　investigations　using　X-ray　CT　and　LBM　demonstrate　that　the　pore　structure　characteristics　and　the　wettability　of　the　pore　walls　significantly　influence　the　two-phase　seepage　process.