Abstract: The triaxial shear tests on three groups of frozen ideal sands are carried out to investigate the evolution rules of particle breakage during shearing process and the effects of particle size on the particle breakage. It is shown that obvious pressure melting of sand samples takes place under -1℃ ~ -2℃ when σ₃ ≥5 MPa, and the strength of frozen sands is even less than the unfrozen strength due to rapid melting near shearing rupture plane at -1℃. The particle breakage of frozen sands occurs during shearing. The particle breakage rate continues to increase with the increase of the axial strain, and even develops with the acceleration after the peak strength under high confining pressure (σ₃ ≥5 MPa). The influences of the particle size of frozen sands on the breakage rate is different from those of unfrozen sands. The particle breakage rate of the frozen sands of small particle group is the largest, which may be related to the action of ice crystals in different parts of frozen soils.