Method for lifting locomotive media reductive nitrogen oxide

The invention relates to a method for improving the efficiency in vehicle that using catalyst to reduction oxide, wherein it comprises: a secondary air feeding tube between the air inlet and the waste gas outlet of engine; at least one flux control valve on the tube, to be controlled by the electric controller, to make the vehicle in low-speed and low discharge temperature start the flux control valve to feed the secondary air to the waste gas outlet, to keep the efficiency that catalyst catalyzes the carbonic oxide and hydrocarbon; and the electric controller has one preset temperature valve, that when then engine discharge temperature is over said valve, the flux control valve will close the valve, to reduce or close the secondary air flux, and reduce the air/fuel ration at the waste gas outlet, to improve the efficiency of catalyst. The invention can improve the transform efficiency of nitrogen oxide, and reduce the nitrogen oxide content discharge to the air.