With the widespread availability of personal computers in the recent past, authors decided to develop a powerful and efficient algorithm to design an optimal leaf spring for a light or heavy truck where the desired objective is the minimum weight of the spring or the spring rate. It is based on the non-linear optimization technique called Lattice Search Method. The software developed is called “YOU HUA” (Chinese for optimization). The computer program has been written using TURBO PASCAL 5.0 for the optimum design solution of the leaf spring. Three types of springs can be designed: symmetrical semi-elliptic, unsymmetrical semi-elliptic and multi-leaf cantilever springs. Some examples are done to illustrate the application of this software. It is concluded that this technique is useful to design an optimal leaf spring with a high level of efficiency and accuracy. This work is a definite contribution in the process of leaf spring design without trial and error.