The influence of calcium carbonate content on particle breakage and macroscopic mechanical properties of calcareous sand was systematically studied by indoor experiment. Experimental results show that the calcium carbonate content of the calcareous sand taken from the South China Sea is 95.8% and the calcareous sand is characterized by the angularity, and high void ratio. The breakage of calcareous sand is essentially result from stress concentration between particles; with the increase of calcium carbonate content and particle size, the friction angles and relative breakage index of calcareous sand increase significantly. Particle breakage not only leads to the particle size distribution into good gradation, but also caused the shear strength envelope expressed nonlinear characteristic under higher normal stress; and with the change of the normal stress and the calcium carbonate content, a set of two variables hyperbola function can be used to describe the change rule of relative breakage index.