Composite materials are nowadays widely used in the engineering field. The general characteristics possessed by the composite material are found to be the reason for using it in the industries. The objective of the paper is to design and optimize a composite leaf spring of Ambassodar car. Leaf springs are commonly used in the suspension system of automobiles and are subjected to millions of varying stress cycles leading to fatigue failure. If the weight of the leaf spring is reduced then the fatigue stress induced in the leaf spring is also reduced. The weight is reduced by replacing seven – leaf steel spring with a mono-leaf composite spring under the identical condition of design parameters. Since the Strength to Weight ratio of composite material is superior that of metals, the weight of the leaf spring is reduced drastically. The composite spring is designed to possess constant cross – section. Both the steel and composite leaf springs are modeled and analyzed using ANSYS 8.1 software. Model developed has been validated using theoretical calculations. Stresses and deflections due to the loading on spring are derived. The finite element results verify that the performance is same as that of steel leaf spring and the stress of the composite leaf spring is found to be lower than that of the steel leaf spring. The composite leaf spring is optimized using ANSYS (Sub Problem Approximation Method) by ‘taking minimizing the weight’ as objective and deflection and stress is taken to be the constraints. A reduction of 60.92% weight is achieved when a seven-leaf steel spring is replaced with a mono-leaf composite spring under identical conditions of design parameters and optimization.