The invention relates to an electric car power supply and a charging and discharging method thereof; the discharging efficiency of a power system can be effectively improved; and the service life of the power battery is prolonged. The technical scheme is that a power battery is provided, and the electric car power supply is characterized in that the power battery is connected in parallel with a super capacitor; when the electric car starts, accelerates or upgrades, the super capacitor supplies current to a driving motor; when the driving motor of the electric car is in a power generation mode, the driving motor charges the power battery and the super capacitor.