Structual　analysis　of　deep　twin-tunnels　is　a　cumbersome　job　due　to　the　complex　mechanism　of　tunnel-ground-tunnel　interactions.　This　paper　deals　with　the　loosening　pressure　on　the　deep　twin-tunnels.　The　deep　twin-tunnel　is　divided　into　three　patterns　based　on　the　different　distributions　of　the　failure　zone.　An　analytical　method　is　proposed　to　predict　the　surrounding　rock　pressure　on　deep　twin-tunnels　through　the　modification　of　the　Protodyakonov＇s　equilibrium　arch　theory　(PEAT).　The　influences　of　the　clear　distance,　reinforcement　coefficient,　excavation　span　and　excavation　height　on　the　loosening　pressure　are　discussed　in　some　details.　The　obtained　results　by　the　proposed　method　are　then　compared　with　the　in-situ　monitoring　data　and　a　reasonably　good　agreement　is　achieved.　The　complementary　studies　suggest　that　the　proposed　approach　is　a　trustable　one　for　the　preliminary　design　of　deep　twin-tunnels.