Polypropylene　fibers　possess　high　strength　and　excellent　abrasion　resistance,　and　have　been　used　to　enhance　concrete　materials.　This　study　investigated　the　influence　of　polypropylene　fibers　on　the　dynamic　compressive　properties　of　seawater　sea-sand　recycled　aggregate　concrete　(SSRAC)　under　three　strain　rates　(10−5,　10−4,　and　10−3/s).　90　specimens　were　prepared,　with　fiber　lengths　of　9,　13.5,　and　18　mm　(the　corresponding　aspect　ratio　of　357,　536,　and　714,　respectively),　and　fiber　contents　of　0.6,　0.9,　and　1.2　kg/m3.　The　test　results　indicate　that　the　polypropylene　fiber　reinforced　SSRAC　specimens　are　more　sensitive　to　strain　rate　in　terms　of　peak　stress　and　peak　strain,　and　the　incorporation　of　fibers　generally　increases　the　peak　stress.　Furthermore,　the　microscopic　morphology　and　nanoindentation　analysis　are　conducted　on　the　interfacial　transition　zone　(ITZ)　of　the　polypropylene　fiber　reinforced　SSRAC.　The　addition　of　polypropylene　fibers　increases　the　local　porosity　of　the　ITZ,　and　reduces　the　bonding　area　between　mortar　and　aggregates,　resulting　in　a　decrease　in　the　elastic　modulus　of　the　ITZ.　This　reduction　effect　varies　with　different　lengths　and　contents　of　fibers,　which　has　a　significant　impact　on　the　peak　stress,　peak　strain,　and　elastic　modulus　of　specimens,　leading　to　some　degree　of　dispersion　in　the　corresponding　strain　effect.　Finally,　a　dynamic　prediction　model　for　fiber-reinforced　SSRAC　is　derived,　which　provides　a　theoretical　basis　for　the　study　of　the　dynamic　mechanical　properties　of　fiber　reinforced　SSRAC.　©　2024　Elsevier　Ltd