To　address　the　strength　damage　of　red　clay　under　dry-wet　cycles,　systematic　conventional　triaxial　tests　under　specific　circumferential　pressure　and　scanning　electron　microscope　observation　were　carried　out　to　describe　the　damage　evolution　of　soil　units　under　load　conditions　of　dry-wet　cycle　red　clay　microunits　based　on　the　Weibull　distribution.　Damage　variable　expressions　obeying　the　Weibull　distribution　were　established　and　the　micro-parameter　pore　area　ratio　and　the　macro-parameter　dry-wet　cycle　number　were　introduced.　The　cross-scale　characterization　of　macroscopic　and　microscopic　parameters　was　realized　by　combining　the　damage　mechanics　equation　of　red　clay　under　loading.　The　microscopic　damage　intrinsic　model　of　red　clay　considering　the　number　of　dry-wet　cycles　was　constructed.　The　model　was　verified　to　be　reasonable　and　effective　based　on　triaxial　tests,　in　which　the　calculation　errors　of　the　secant　modulus　damage　threshold,　probability　density　function　shape　parameter,　and　dry-wet　cycle　red　clay　damage　stress　were　within　10　%,　5　%,　and　5　%,　respectively.　©　2024　ASTM　International.　All　rights　reserved.