Abstract: An approach based on integral transformation, dual form of wave motion equation and precise integration method (PIM) is presented to evaluate the dynamic stiffness of strip foundation resting on soils that are fluid-filled poroelastic. The two-phase behavior of the porous medium is represented according to Biot's theory. Fourier integral transform is used with respect to the x-co-ordinate, and the wave equations are reduced to ordinary ones. Considering the different contact conditions between the soil and foundation which are pervious or impervious, the PIM solution in the wave-number domain of the problems is achieved. With the aid of Inverse Fourier transforms of Green's function in the wave-number domain, the relationship between force and displacement in the physical domain is obtained. Finally, a numerical example is calculated to show that the proposed PIM can provide accurate results for solutions of dynamic stiffness of strip foundation. Besides, the technique can be applied to the computation of two groups of examples to analyze the influence of the porosity and seepage force.