The invention relates to a compressed air self-supply engine running system and method. The system comprises an engine, an air compressor impeller, an air compressor, an air compressor air storage tank, an air booster pump, a high-pressure air storage tank I and a high-pressure air storage tank II; an exhaust port of the engine is connected with an air inlet of the air compressor impeller, an exhaust port of the air compressor impeller is connected with an air inlet of the air compressor air storage tank, and an exhaust port of the air compressor air storage tank is connected with the air booster pump; and the air booster pump is connected with an air inlet of the high-pressure air storage tank I through a valve I and connected with an air inlet of the high-pressure air storage tank II through a valve II, an exhaust port of the high-pressure air storage tank I is connected with a valve IV, an exhaust port of the high-pressure air storage tank II is connected with a valve III, and the valve III and the valve IV are connected with the engine. The invention further discloses a compressed air self-supply method. Waste of the compressed air self-supply engine is recycled to supplement compressed air so that running time of the air engine can be guaranteed, the problems that a gas station needs to be built for gas inflation or high-pressure air storage tanks need to be replaced due to insufficient pressure are solved, and energy conservation and environmental protection are achieved.