GDS hollow cylindrical apparatus was used to investigate the softening characteristics of soft clay under different effective confining pressures and different cyclic stress ratios. The test results show that the rotation of the principal stress axis makes the soil easier to soften. With the loading cycles increasing, the torsional stress strain hysteresis curves of soil are different from each other, and the shear modulus of soil decreases. Under the same effective confining pressure, the softening index of soil decreases gradually with the increasing cyclic stress ratio. Under the same cyclic stress ratio, the softening index of axial and shear modulus soil decreases with increasing effective confining pressure.