With regard to a horizontal sand drainage cushion on natural ground, a parameter study using the plane strain finite element method was carried out to investigate the effects of the parameters of the sand cushion and ground on the efficiency of ground consolidation. The influences of the permeability, thickness, and width of the sand cushion on ground consolidation were considered, together with the permeability and thickness of ground soil. Meanwhile, a lumped parameter for the sand cushion and ground soil was adopted, and its relationship with the ground consolidation efficiency was analyzed. It was found that the permeability of the sand cushion on natural ground required by the existing technical specification was unreasonable. The ground consolidation efficiency increases nonlinearly, in a hyperbolic manner, with the lumped parameter. There exists a certain value of the lumped parameter that can meet the requirements of optimum consolidation efficiency. This value can be used as a controlling index for designing a sand cushion on the ground with various soil conditions.