Red　clay　exhibits　unique　engineering　properties　and　is　prone　to　excessive　settlement,　uneven　settlement,　and　other　forms　of　damage　in　roadbeds　under　traffic　loading.　To　clarify　the　key　influencing　factors　and　evolution　laws　of　settlement　and　deformation　in　red　clay　roadbeds,　this　study　analyzed　the　undrained　cyclic　cumulative　deformation　behavior　of　saturated　red　clay　through　dynamic　triaxial　tests.　The　results　showed　that　the　cumulative　deformation　of　red　clay　decreases　with　increasing　compaction　degree　and　decreasing　cyclic　stress　ratio　(CSR).　When　the　CSR　increases　from　0.2　to　0.4,　the　difference　in　cumulative　deformation　between　red　clay　with　compaction　degrees　of　90%　and　98%　increases　by　a　factor　of　25.　Specifically,　by　reducing　the　CSR　during　compaction,　the　cumulative　deformation　of　red　clay　subgrades　can　be　effectively　controlled.　Based　on　the　defined　relative　cyclic　stress　ratio　parameter,　this　study　constructed　a　critical　cyclic　stress　ratio　prediction　model　and　a　cumulative　deformation　prediction　model,　which　enable　the　prediction　of　undrained　cumulative　deformation　of　saturated　red　clay　under　any　number　of　loading　cycles.　This　work　can　provide　theoretical　guidance　for　compaction　control　and　settlement　prevention　techniques　for　red　clay,　thereby　effectively　improving　the　stability　and　durability　of　roadbeds.