Submarine electric propulsion is a huge system engineering, which involves the key steps of power generation, power transmission, power transformation, propulsion and energy storage. At the same time, as a high-power pulse power supply, supercapacitor can also be used in the power supply system of directional energy weapons. The application of super capacitor with battery in the electromechanical starting system of internal combustion engine can effectively protect the battery, prolong its service life, reduce its equipped capacity, especially in the case of low temperature and battery power loss, to ensure reliable starting. The discharge capacity of the battery in low temperature environment is obviously reduced, which will cause the tank and combat vehicle unable to start, which affects the military combat readiness. The working temperature range of the super capacitor is wide, and it can work at - 40 ℃. It ensures the normal power supply of the electric starting system and makes the tank and combat vehicle start successfully at one time.