Steel plastic reinforced geogrid is a composite of steel plastic reinforced strips through a novel process. Due to the regular coarse pattern on the surface of this product, it is laid in the replacement soil layer to withstand huge stress resistance and friction with the filling soil. Overall, it limits the shear, lateral extrusion, and uplift of the foundation soil. Due to the high stiffness of the reinforced soil cushion, it is conducive to the diffusion and uniform transmission of upper foundation load, distributed to the underlying soft soil layer, The bearing capacity of the foundation has been improved. Due to the role of reinforced soil cushion, the overall stiffness of the foundation within the compression layer range has been increased, which is conducive to adjusting the deformation of the foundation. The reinforced soil composite cushion formed by using steel plastic reinforced geogrid is a flexible structure that can absorb earthquake energy well, so its seismic performance is good.