Using fast lagrangian analysis of continua in 3 dimensions (FLAC3D) which is based on finite difference method (FDM), stresses and displacements of a cement concrete slab with a void beneath the slab corner were obtained. The concrete slab was assumed to be a cantilever slab, and the cushioning effect of the road base was taken into consideration. The hypothesis and the difference of the results computed by FLAC were analyzed. A comparative analysis also was conducted between the FLAC calculations and traditional structural calculations. The results indicate that when the concrete slab is assumed to be a cantilever slab, the values of stress and displacement by traditional methods are quite smaller than those by derived using FLAC 3D because the influence of loading eccentricity is not considered in structural calculation. In the FLAC calculations when the road base cushioning effect is considered, the tensile stresses and displacements in the slab decline. Some tensile stresses appear in subgrade soil, however. Therefore, more efforts should be made to enhance the subgrade soil strength.