Abstract: The compaction degree of sandy soil has a significant influence on the shear strength. However, quantitative analyses of the shear strength of sandy soil with different void ratios have not been given directly in the existing researches. The target strength value can be obtained by controlling the initial void ratio of sandy soil, which has a certain application prospect in the geotechnical similarity model tests. Based on the critical state theory of sand, theoretical expression of void ratio on the shear strength is established. A series of geotechnical tests are carried out for copper tailings and tungsten tailings collected from tailings pond sites. Using the derived theoretical expression, the shear strength of tailings in different states is analyzed. The results show that the shear strength of sandy soil decreases nonlinearly with the increasing void ratio. The shear strength of sandy soil decreases more slowly with the larger void ratio. The experimental results confirm that the theoretical expression of void ratio on the shear strength can reasonably describe the shear strength of tailings under different void ratios.