Wave load causes continuous rotation of the principal stress axes of seabed soil.Unlike seismic load and traffic load, under the action of cyclical wave load, stiffness softening of soft clay is much more obvious.Numerical simulation is applied to obtain the stress response of undisturbed and disturbed seabed soil, and to analyze the characteristics of the stress path.Under wave loads, the main feature of the seabed soil is the continuous rotation of its maximum principal stress axis;the maximum principal stress' cycle is similar to the wave load cycles.Under the influence of the structure in the seabed disturbance, the soil's stress path changed under the wave load, and the factors that affect the stress path can be generalized using the initial principal stress orientation, the initial stress ratio, the angle of the major principal stress direction, and other factors.To describe the relation of a soil's stress and strain after stiffness softening, two parameters were introduced to the Haridin-Drnevich model to reflect the stiffness softening and cumulative plastic strain phenomenon, and these two parameters are a function of the soil's initial status, which influences its stress path under wave load.The cyclic coupling shear tests can probably simulate the wave load and therefore, this modified Haridin-Drnevich model should be compared with the results of cyclic coupling shear tests where wave loads can be applied to verify its reliability.