A way to improve the existing hybrid vehicles is the global optimal design of their components when related to their actual use. This paper proposes a global optimal design method for Power-Split Hybrid Electric Vehicles (PS-HEVs) equipped with an Electric Variable transmission. A genetic algorithm is used to optimize system parameters. The process includes Discrete Dynamic Programming for an optimal energy management. The optimization focuses on the minimization of two objectives that are fuel-consumption and number of battery cells. Pareto fronts are depicted and compared for different drive cycles and show the existence of a possible trade-off between fuel-consumption and battery size.