In today’s world, the road and surface failure of the flexible pavement has become the most important and attention diverting problem, which may be due to the low quality of materials used, less and inadequate experience of the technical staff, and errors that may occur during the designing of the pavement. The design of thickness of the flexible pavement has taken the backbone place in determining the overall performance and providing high level of serviceability of the pavement structure for the heavy traffic loads under the adverse climatic conditions, during the expected design period. The aim of this research is to develop software for the flexible pavement design based on the AASHTO, Group Index, and CBR. This software can be used to determine the thickness of each layer, design life evaluation, knowing the relative damage factor, finding the various design variables like calculating the structural number and equivalent single axle load etc and climatic effects. The results obtained from this software were analyzed and compared with the theoretical (manual) design and with the DARWin, a design software of AASHTO, and were found absolutely feasible and accurate. This flexible Pavement software can save the precious time and avoid the errors and difficulties occurring during the conventional methods of design.