Aluminum-air battery (AAB) is a very promising energy generator for electric vehicles (EVs) due to its high theoretical capacity and energy density, low cost, earth abundance, environmental benignity and rapid refuel. In this study, the practical energy efficiency and power density of AAB are improved by optimizing its factors, such as anode-cathode distance, operation temperature, electrolyte flow rate and the atmosphere. Under air atmosphere, the peak power density reaches 381 mW cm(-2), and the optimum output power density is 258 mW cm(-2) with the anode efficiency of 90.9% and energy efficiency of 44.4%; and under pure O-2 atmosphere, the peak power density is up to 545 mW cm(-2), and the optimum output power density is 430.5 mW cm(-2) with the anode efficiency of 94.2% and energy efficiency of 42.6%. These results are promising to constitute a foundation for future development of Al-air battery systems for EVs.