With　the　development　of　marine　infrastructure　construction　in　recent　years,　the　durability　requirements　of　cement-based　materials　in　marine　environments　have　been　increasingly　raised.　Ferroaluminate　cement　is　the　＂third-generation　cement＂　in　China,　which　has　excellent　performance　of　resistance　to　seawater　erosion.　The　purpose　of　this　study　was　to　explore　the　mechanical　properties　and　microstructural　changes　of　ferroaluminate　cement　concrete　(FACC)　and　ordinary　Portland　cement　concrete　(OPCC)　under　the　seawater　dry-wet　cycle,　with　particular　attention　to　the　influence　of　water-to-cement　ratio　on　the　properties.　The　physical　and　mechanical　properties　such　as　mass　loss　rate,　relative　dynamic　elastic　modulus　and　cube　compressive　strength　of　FACC　and　OPCC　were　compared　and　analyzed　by　experiments,　and　the　microstructure　was　analyzed　by　scanning　electron　microscope　and　mercury　intrusion　method.　The　results　show　that　during　the　seawater　dry-wet　cycle,　FACC　has　a　lower　mass　loss　rate,　and　the　relative　dynamic　elastic　modulus　of　FACC　increases　at　the　beginning　of　the　seawater　dry-wet　cycle　and　then　tends　to　be　stable,　while　relative　dynamic　elastic　modulus　of　OPCC　shows　a　significant　decrease　in　the　later　stage　of　the　seawater　dry-wet　cycle.　In　terms　of　compressive　strength,　FACC　increases　after　seawater　dry-wet　cycle,　while　OPCC　decreases.　Overall,　FACC　demonstrates　superior　durability　and　stronger　resistance　to　seawater　erosion　compared　to　OPCC.　Microscopic　analysis　reveals　that　FACC　has　lower　porosity　and　finer　pore　structure,　which　contributes　to　improve　its　durability.　©　(2025),　(Bulletin　of　the　Chinese　Ceramic　Society　Press).　All　Rights　Reserved.