This　paper　is　aimed　at　the　problem　of　inaccurate　calculation　of　the　water　inflow　of　a　foundation　pit　with　a　suspended　water-proof　curtain　in　a　confined　water　stratum.　According　to　the　groundwater　hydraulics　principle,　the　theoretical　model　of　the　seepage　field　of　the　foundation　pit　is　established,　and　the　analytical　formula　of　the　water　inflow　for　the　circular,　strip,　and　rectangular　foundation　pits　is　deduced.　The　seepage　path　influence　coefficient　alpha　related　to　the　water-proof　curtain　insertion　ratio,　the　thickness　of　the　confined　aquifer,　and　the　radius　of　the　foundation　pit　is　proposed　and　obtained　by　the　positive　and　negative　analysis　of　numerical　simulation.　The　coefficient　is　used　to　correct　the　equivalent　seepage　length　in　the　pit　and　directly　affect　the　calculation　result　of　water　inflow.　Finally,　based　on　the　calculation　results　of　the　analytical　solution　of　water　inflow,　the　relationship　between　the　scale　of　the　foundation　pit　and　the　water　control　effect　is　discussed.　The　research　results　show　that　the　theoretical　analysis　results　in　this　paper　are　in　good　agreement　with　the　numerical　results　and　the　measured　data　in　the　field:　when　the　size　of　the　foundation　pit　is　too　large,　it　is　not　suitable　to　use　the　suspended　water-proof　curtain　as　the　water　control　measure.