In this paper, the study was conducted on the subject of the hybrid electric vehicles used by the military, and optimized the propulsion system for fuel economy considering energy supply to the mission equipments. For the analysis of the vehicles, a method based on the geometry and some assumptions was applied with basic vehicle dynamics. The sources of energy supply in the military hybrid electric vehicles are an engine, a battery and an ultra-capacitor. The optimal operation point among an engine, a battery and an ultra-capacitor can be found by minimizing energy consumption of driving power train and mission equipments. In the study, it was possible to find the optimal propulsion system by comparing fuel efficiency of the vehicles during the driving cycle.