To explore the effect of particle shape on the ultimate particle size distribution of carbonate sands under the condition of large shear strain, a series of ring shear tests and particle shape analyses were carried out on carbonate sands taken from the South China Sea using the ring shear apparatus and the Morphologi G3. The results show that an ultimate grading, as a result of the particle breakage, is reached after large shear strains in the ring shear apparatus. However, due to the more irregularity of the intact sands than the crushed sand, a significant breakage is induced when recreating a sample by mixing intact soil required for the ultimate size grading. As a result, the fractal dimension of the sample replaced with a different particle shape is bigger than that of the sample with the particle remolded.