Abstract: The irregular morphology and fragile nature of coral sands result in distinctive compression behavior, posing significant challenges for settlement control of engineering structures in coral sands area. Confining compression tests of coral sands with different particle sizes, gradation characteristics, water content, and initial pore ratio were carried out to analyze its compression characteristics in different conditions and to clarify the influencing factors of its compression characteristics. The results show that the distribution of coral sands with large particle size (D=2−5 mm) can be optimized by the sharp-angle fracture or particle breakage. The particle breakage of small particle size coral sands (D<2 mm) is mainly caused by grinding, which has limited effect on the optimization of gradation. The coral sands with larger median particle size D₅₀ have smaller compression deformation in lower vertical pressure P (P≤50 kPa), and larger compression deformation in higher P (P>400 kPa). The compressibility of coral sands with larger inhomogeneity coefficient is also greater. Water content has little influence on compressibility under low vertical pressure (P≤50 kPa); however, under higher pressure P (P>50 kPa), the compression deformation of coral sands with 10% water content w was the largest. When the loading gradient ΔP does not exceed 200 kPa, the coral sands with 10% water content have the largest compressive deformation; when ΔP exceeds 200 kPa, the larger ΔP, the largest compressive deformation, and the higher the water content of the coral sands. The larger the initial porosity ratio, the higher the compressibility of coral sands, and the compressive deformation under each gradient increased nonlinearly with ΔP. The lateral limit compression process of coral sands can be categorized into two stages with the rate of change of pore ratio: compaction stage (P≤100 kPa) and particle crushing (P>100 kPa). The results are important to guide significance for the design and construction of filling projects and the settlement control and safe operation of structures in the coral sands area.