The　calcareous　sand　is　widely　used　as　the　construction　materials　in　marine　engineering.　Particle　breakage　will　reduce　the　strength　and　dilatancy,　and　increase　the　compressibility,　which　affects　the　security　and　stability　of　the　constructions.　In　this　study,　the　influences　of　breakage　on　the　position　and　shape　of　the　critical　state　line　are　described　by　introducing　the　crushing　stress.　A　unified　state-dependent　fractional　plastic　flow　rule　is　established　based　on　fractional　differential　and　state-dependent　theory.　A　fractional-order　plasticity　boundary　surface　constitutive　model　considering　the　particle　breakage　and　state-dependent　behavior　of　the　calcareous　sand　is　established　under　the　framework　of　the　boundary　surface　plasticity　and　the　critical　state　theory.　The　model　can　simulate　the　drained　triaxial　test　results　of　the　calcareous　sand　under　different　initial　densities　and　confining　pressures　and　reflect　the　state-dependent　behavior　under　the　influences　of　the　particle　breakage,　which　verifies　the　applicability　of　the　proposed　model.　©　2023　Chinese　Society　of　Civil　Engineering.　All　rights　reserved.