The fluid-solid-coupling issue is very important both theoretically and practically. The mathematical model on the one-dimension nonlinear fluid-solid-coupling issue is established after taking into account the feature that the seepage coefficient and porosity of deformable porous media depends on the change of pressure, introducing the relationship between permeability coefficient and permeability rate, and combining the mass conservation equation and continuity equation of nonlinear flow. Based on the Dacy law and mass conservation law, the differential equation of unsteady flow is derived, in which the porosity change has been taken into account. Besides, the analytical solution which reveals the relationship between pore water pressure with time and space has been deduced by applying the method of separation of vari　ables and combining with the boundary conditions and initial conditions, and the effect that the control parameter of flow equation on the nonlinear degree of flow is also analyzed. The change of flow with the time is treated by introducing the physical parameters in the course of analysis and the nonlinear flow mechanism is elucidated. At last, the factors influencing the flow pressure are analyzed qualitatively.