Abstract: This paper investigates the influence of clay contents on the shear strength characteristics of sand clay mixture by ring shear test. A series of consolidated drained ring shear tests are conducted under the axial loads of 75, 150, 300, and 600 kPa. The relationship between shear stress and rotation angle is obtained. According to the peak shear stress obtained from experimental results and the Mohr-Coulomb failure criterion, the cohesion and friction angle are obtained. The cohesion value is located between 5 kPa and 18 kPa, and it goes to the minimum value when the clay content is around 50%. The internal friction angle decreases with the content of clay, and the decreasing trend is more significant when the clay content exceeds 50%than that one lower than 50%.