Coral　sand　particles　exhibit　a　wide　range　of　shapes,　which　can　be　divided　into　four　shapes,　e.g.,　blocky,　dendritic　and　rodlike,　flaky,　and　shell　debris.　The　particle　shape　of　these　mixtures　is　defined　by　the　sphericity,　concavity,　aspect　ratio,　flatness　and　overall　regularity,　which　ranges　from　0　to　1.　The　effect　of　particle　shape　on　the　strength,　crushing　characteristics,　and　critical　state　parameter　is　systematically　investigated　through　a　series　of　triaxial　drainage　shear　tests　under　different　confining　pressures.　And　the　relationship　between　critical　state　parameters　and　mechanical　parameters　is　established.　The　test　results　demonstrate　the　existence　of　an　evident　strain-hardening　phenomenon　in　the　stress-strain　curve　of　coral　sand,　accompanied　by　a　strain-softening　phenomenon　when　the　bias　stress　reaches　its　peak　value.　The　sample　is　initially　subjected　to　shear　shrinkage,　followed　by　shear　expansion.　The　volumetric　deformation　of　the　coral　sand　decreased　with　increasing　peripheral　pressure.　The　particles　are　transformed　from　rough　irregular　shapes　to　smooth　spheres　as　evidenced　by　an　increase　in　the　shape　parameter.　The　greater　the　degree　of　irregularity　in　the　shape　of　the　particles,　the　more　pronounced　the　resulting　change　in　size　reduction.　In　addition,　the　critical　state　parameter　was　found　to　be　influenced　by　the　shape　of　the　coral　sand　particles　and　the　mode　of　particle　accumulation.　The　overall　shear　resistance　of　coral　sand　particles　was　found　to　depend　on　particle　rearrangement　in　addition　to　particle　surface　roughness　and　interparticle　friction.　It　is　proposed　that　the　general　regularity　critical　state　parameter　equation　relates　the　particle　shape　of　coral　sand　to　its　critical　state　mechanical　properties,　which　is　of　great　importance　to　the　practical　application　and　research　of　coral　sand　in　engineering,　and　provides　an　effective　means　of　predicting　mechanical　properties　granular　materials.