Red　clay　is　a　special　soil　that　loses　water　and　shrinks　easily,　which　causes　expansion　and　contraction　and　leads　to　the　generation　and　development　of　cracks,　weakening　the　strength　and　engineering　properties　of　the　soil.　This　investigation　analyzed　the　mechanism　of　crack　evolution　and　patterns　of　strength　decay　in　red　clay　under　dry-wet　cycles　and　established　a　relationship　between　strength　and　crack　ratio　by　employing　image　processing　techniques　and　conducting　direct　shear　tests　on　red　clay　with　various　initial　moisture　contents　and　humidification　times.　The　results　show　that　the　crack　ratio　increases　with　the　number　of　dry-wet　cycles　and　eventually　tends　to　be　stable　after　the　fourth　dry-wet　cycle,　and　the　stress-displacement　curve　of　red　clay　changes　from　weak　hardening　to　hardening.　With　the　progress　of　the　dry　and　wet　cycles,　the　shear　strength　indexes　of　red　clay　decrease　extensively,　displaying　a　negative　association　with　the　sample＇s　initial　moisture　content　and　the　duration　of　humidification.　Based　on　the　experimental　result,　a　quadratic　function　was　established　to　model　the　relationship　between　soil　cracking　ratio　and　shear　strength,　which　can　predict　the　shear　strength　of　red　clay　from　the　cracking　ratio.