Sub-grade soil stabilization is one of the primary and major processes in the construction of any highway. The aim of this research paper is to formulate a model based on Genetic Algorithm which can be used to predict variation in the values of CBR of the Sub-grade Soil with the addition of a specific percentage of Fly Ash. The input values for this study were those which directly affect the CBR values i.e., directly proportional to CBR. It includes Liquid Limit (LL), Plasticity Index (PI), Optimum Moisture Content (OMC) & Fraction of Fly Ash added (F.A in %).For analysis of stabilization of soil using fly ash, Evolver 5.7 an add-in software of excel is used. Properties used for analysis are Liquid Limit, Plastic Limit, Optimum Moisture Content and California Bearing Ratio. This model will help all types of agencies involved in road construction like NHAI, Infrastructure Developers and Construction Contracting Organizations to pre-determine the soil stabilization achieved due to fly ash for a particular type of sub-grade soil.