The advantages and shortcomings of traditional method and Finite Difference Method (FDM) for the calculation of cantilever slab model with void beneath cement concrete slab corner and analysis on the results were carried out. The traditional method assumes that the cement concrete slab with void below was a cantilever slab with constant sections. The influence of loading eccentricity was not considered while more than two wheel loads were exerted on the concrete pavement, which can be overcome by using Finite Difference Method. With FDM, the stress and displacement distributions of any parts of the cement concrete slab can be easily achieved. The results indicate that when the concrete slab with void beneath the slab corner was assumed to be a cantilever slab, regardless of calculation by traditional method or by FDM, the cement concrete pavement will be destroyed even under the condition of minimum traffic grade. The fatigue stress and road deflection obtained by FDM are bigger than that obtained by the traditional formula, so bigger safety factor should be employed in the road design.