The　stability　of　the　excavation　face　plays　a　pivotal　role　in　ensuring　the　safety　control　of　shield　tunneling.　However,　there　is　a　dearth　of　existing　literature　on　the　investigation　of　excavation　face　stability　in　inclined　composite　strata　under　the　influence　of　seepage.　This　paper　conducts　model　tests　to　investigate　the　instability　of　excavation　faces　in　inclined　strata　under　varying　seepage　conditions　(three　cases).　It　examines　the　variations　in　effective　support　pressure,　surface　settlement,　and　earth　pressure　throughout　the　process　of　instability.　The　experimental　results　were　validated　through　numerical　simulation.　The　instability　zone　and　deformation　modes　are　subjected　to　a　comprehensive　analysis.　The　results　indicate　that　the　presence　of　seepage　enhances　the　limit　support　pressure,　consequently　reducing　the　required　backward　displacement　to　attain　such　pressure.　The　presence　of　seepage　(k　=　1.0　and　k　=　0.5)　exerts　a　more　pronounced　influence　on　surface　settlement,　leading　to　amplified　surface　collapse　when　compared　to　the　no-seepage　case　(k　=　0).　The　influence　extent　in　front　of　the　excavation　face　gradually　increases　as　the　value　of　k　increases.　The　soil　arching　effect　is　significantly　weakened　due　to　the　influence　of　seepage,　leading　to　substantial　surface　collapse.　The　findings　of　this　study　offer　valuable　insights　into　the　operational　strategies　for　shielding　in　water-rich　silty　clay　layers　overlying　sandy　cobble　strata.