The invention discloses a vehicle and an engine thereof. The engine comprises a plurality of air cylinders, a plurality of exhaust pipes, an air supply pipeline and a valve arranged on the air supply pipeline, wherein the air supply pipeline can replenish the plurality of exhaust pipes with air; through the arrangement, the air supply pipeline replenishes the exhaust pipes with fresh air, the fresh air further replenishes incompletely combusted exhaust gas discharged into the exhaust pipes with oxygen, so that the incompletely combusted exhaust gas can be continuously combusted in the exhaust pipes to be discharged into the air, and the quantity of incompletely combusted exhaust gas discharged into the air is reduced.