The evaluation of the wave-induced residual pore pressure in a porous seabed is vital for the prediction of the potential of seabed instability under the combined action of waves and currents. Based on the Biot’s quasi-static consolidation model, decoupled models were used to separately discuss oscillatory pore pressure and cumulative pore pressure, which ignores the inertia effects due to the acceleration of solid particles. In this paper, considering coupling effect between oscillatory and cumulative pore pressure, a partially dynamic model (u-p) coupled model for soil dynamic response under wave-current interaction was proposed. Upon comparison with existing laboratory experimental data, the capacity of the proposed coupled method is demonstrated. A series of parametric studies were conducted to analyze the influence of wave characteristics and soil parameters on cumulative pore pressure and corresponding liquefaction. The research results indicate that changes in wave height, water depth, and relative density greatly affect the development of cumulative pore pressure and the maximum liquefaction depth; Comparing to the quasi-static (QS) coupled model, the maximum liquefaction depth of the partially dynamic (u-p) is often bigger, which accounts for the influence of soil particle acceleration on pore pressure accumulation.