The　discharge　of　seepage　water　from　undersea　tunnel　structures,　often　treated　as　wastewater,　inherently　carries　a　substantial　reservoir　of　untapped　low-grade　thermal　energy.　Unfortunately,　comprehensive　investigations　into　harnessing　this　latent　potential　remain　notably　limited.　This　study　introduced　an　innovative　strategy　through　the　design　of　an　undersea　tunnel　seepage　seawater　source　heat　pump　system.　Distinguished　by　the　integration　of　a　capillary　front-end　heat　exchanger,　this　system　aimed　to　effectively　exploit　the　frequently　disregarded　low-grade　thermal　energy　present　in　the　seepage　water　of　undersea　tunnel　structures.　The　seawater　seepage　from　the　tunnel　is　transported　to　the　car　park　at　the　tunnel　entrance,　and　a　seawater　energy　pool　is　constructed　by　storing　seawater　in　its　underground　space.　The　use　of　capillary　network　placed　in　the　energy　pool　in　the　front　heat　exchanger,　water　source　heat　pump　units,　circulating　water　pumps　and　fan　coil　end　device　composed　of　underground　undersea　tunnel　seepage　seawater　source　heat　pump　system　for　the　building　heating　and　cooling.　Furthermore,　a　comparative　assessment　was　conducted,　contrasting　this　novel　system　with　the　traditional　air-conditioning　setup　that　utilizes　chillers　and　gas　boilers　as　cooling　and　heating　sources.　The　aim　was　to　evaluate　its　capacity　for　energy　conservation　and　emission　reduction.　The　findings　from　the　study　strongly　affirmed　the　viability　of　the　proposed　seepage　seawater　source　heat　pump　system　within　undersea　tunnels.　It　boasted　the　potential　to　achieve　annual　savings　of　53.55　tce,　highlighting　a　noteworthy　energy-saving　rate　of　21.2%.　Concurrently,　reductions　in　CO2,　SO2,　and　particulate　emissions　amounted　to　132.28　t/a,　1.07　t/a,　and　0.54　t/a,　respectively.　This　study　not　only　stands　as　a　reference　for　the　strategic　utilization　of　seepage　seawater　from　undersea　tunnel　structures,　prioritizing　energy　conservation　and　emission　reduction,　but　also　pioneers　innovative　approaches　toward　resource　optimization　and　environmental　sustainability,　meeting　the　inherent　needs　of　carbon　peaking　and　carbon　neutrality　goals.